Production of minor lymphocyte stimulatory-1a antigen from activated CD4+ or CD8+ T cells

Minor lymphocyte stimulatory (Mls) Ag are super Ag that stimulate a high proportion of T cells of a specific TCR V beta family. One of the super Ag, Mls-1a, which is recognized mainly by TCR V beta 6+ and V beta 8.1+ T cells, has recently been linked to the response to product of the open reading frame in 3'-long terminal repeat of endogenous mammary tumor virus, MTV-7. It is quite certain that B cells are able to produce and also to present the Mls-1a Ag. However, it remains to be determined whether other cell types, especially T cells, produce Mls-1a Ag. In this study using highly purified T cell subpopulations, capacity to produce Mls-1a Ag was analyzed by calculating the proportion of Mls-1a reactive V beta 6+ or V beta 8.1+ T cells in responding cell populations. We found that nonstimulated CD8+ T cells produced a low amount of Mls-1a Ag, and the capacity to do so was considerably increased by stimulation with immobilized anti-TCR mAb. By contrast, nonstimulated CD4+ T cells did not produce Mls-1a Ag at all. Even when CD4+ T cells were activated via TCR signaling with immobilized anti-TCR mAb, CD4+ T cells did not produce Mls-1a Ag. However, CD4+ T cells primed with conventional Ag in vivo produced Mls-1a Ag on restimulation with that specific Ag in vitro. These findings indicate that not only CD8+ T cells but also CD4+ T cells can produce Mls-1a Ag on appropriate stimulation, although different mechanisms for Mls-1a production may operate between the CD4+ and CD8+ T cells.

Influence of a small number of mature T cells in donor bone marrow inocula on reconstitution of lymphoid tissues and negative selection of a T cell repertoire in the recipient

Allo-chimerism and clonal elimination of self antigen (Ag) (Ia + Mls-1a) reactive V beta 6+ T cells were analyzed and compared between allogeneic bone marrow (BM) chimeras reconstituted with BM cells which had been treated with anti-Thy-1 monoclonal antibody (mAb) plus complement (C) (T- chimeras) and BM chimeras which had been reconstituted with BM cells pretreated with anti-Thy-1 mAb alone (T+ chimeras). When lethally irradiated AKR (Mls-1a) mice were reconstituted with BM cells from B10 or B10 H-2 congenic mice, both T+ and T- chimeras were entirely free of signs of graft-versus-host reaction (GVHR). However, complete replacement of the AKR lymphoid tissues by donor BM cells was accomplished at an early stage in T+ chimeras but not in T- chimeras. On the other hand, clonal elimination of V beta 6+ T cells reactive to the recipient Ag (Mls-1a) was abolished in T+ chimeras but successfully induced in T- chimeras. The V beta 6+ T cells not eliminated in T+ chimeras showed depressed responses against Mls-1a antigens. The findings herein demonstrate that T cells which contaminate a BM inoculum survive in recipient mice after treatment with anti-Thy-1 mAb without C in vitro followed by BMT. The surviving T cells have been estimated to represent fewer than 0.5% of the BM cells inoculated. These cells appear to accelerate the full replacement of recipient lymphoid tissues by donor cells. Furthermore, the T cells which survive in the marrow inoculum influence eventually the development of a tolerant state in the T cell repertoire of the donor.

Prolactin acts on the extreme 5' portion of MMTV LTR involving a mammary cell-specific enhancer

We have previously shown that a human mammotropic polypeptide hormone, prolactin (PRL) can act synergistically with steroid hormones to regulate gene expression directed by the long terminal repeat of mouse mammary tumor virus (MMTV LTR) in a human ductal carcinoma cell line T47D cells using a chloramphenicol acetyltransferase reporter gene system and gene transfection methods. In the present study, using various recombinant plasmids we analyzed functional elements in the MMTV LTR that is essential for the PRL responses. We show that the PRL-responsive elements are located in the extreme 5' end of the MMTV LTR, a region previously described by others to be a mammary cell-specific enhancer.

Reconstitution of lymphoid tissues under the influence of a subclinical level of graft versus host reaction induced by bone marrow T cells or splenic T cell subsets

Reconstitution of lymphoid tissues under the influence of subclinical graft versus host reaction (GVHR) has been investigated. Lethally irradiated AKR mice were reconstituted with B10 bone marrow (BM) cells which had been treated with anti-Thy-1 antibody alone without complement (GVHR chimera). Their immunological reconstitution was analyzed and compared with that of AKR recipients which had been reconstituted with B10 BM cells treated with anti-Thy-1 antibody plus complement (control chimera). One hundred percent of both chimeras survived more than 100 days without showing clinical signs of GVHR. However, full donor chimerism was accomplished at an early stage after reconstitution in the former GVHR chimeras, whereas a substantial number of recipient T cells persisted in control chimeras for the entire observation period. When reconstitution of various lymphoid tissues was compared between control and GVHR chimeras, no difference in the reconstitution of the thymus and spleen was noted. By contrast, the cellularity of peripheral lymph nodes in GVHR chimeras was regularly considerably lower than that of the control chimeras. The apparent insufficiency of lymph node reconstitution appeared to be attributable to the impairment of lymph node structure itself which may be involved in lymphocyte homing. Furthermore, clonal deletion of V beta 6+ T cells which are reactive to recipient (Mls-1a) antigens was abrogated in the GVHR chimeras but was normally induced in the more completely T cell-depleted control chimeras. This abrogation of clonal deletion of V beta 6+ T cells appeared to result from the early disappearance of recipient T cells in these chimeras. Thus, it appeared that donor T cells in the BM that survive anti-Thy-1 treatment in vitro plus subsequent BM transplantation induced a subclinical level GVHR which contributed to the full donor chimerism as well as abrogation of clonal elimination of V beta 6+ donor T cells. Indeed, inoculation of CD8+ T cells along with the transplantation of the T cell-depleted BM cells (anti-Thy-1 plus C-treated cells) from donor mice into the AKR recipients was also shown to induce a similar state in the recipients.

Transcriptional down-regulation of tumor necrosis factor-alpha gene expression by a synthetic peptide homologous to retroviral envelope protein

We have previously shown that a synthetic peptide (CKS-17) homologous to retroviral envelope protein suppresses the accumulation of superantigen staphylococcal enterotoxin-induced TNF-alpha mRNA in human PBMC and in highly purified human monocytes. The present study was designed to examine the underlying mechanism(s) by which CKS-17 down-regulates the TNF-alpha mRNA expression using a human acute monocytic leukemia cell line THP-1 stimulated with the superantigen staphylococcal enterotoxin E. A cyclooxygenase inhibitor indomethacin does not reverse the inhibition of TNF-alpha mRNA expression by CKS-17, suggesting that prostaglandins are not responsible for the suppressive action of CKS-17. The inhibitory effect of CKS-17 is, however, significantly blocked by a protein synthesis inhibitor cycloheximide, indicating that CKS-17 requires de novo protein synthesis to induce the suppressive activity. The mRNA stability assays using actinomycin D show that CKS-17 does not decrease the TNF-alpha mRNA stability. Nuclear run-on transcription assays further reveal that CKS-17 suppresses the TNF-alpha mRNA transcription rate. Taken together, these results suggest that the synthetic retroviral peptide CKS-17 down-regulates TNF-alpha mRNA expression through inhibition of transcriptional activation of the TNF-alpha gene, which requires de novo synthesis of a transcriptional repressor protein(s).

Diversification, not use, of the immunoglobulin VH gene repertoire is restricted in DiGeorge syndrome

Immunoglobulin (Ig) genes were isolated from unamplified conventional as well as polymerase chain reaction-generated cDNA libraries constructed from the peripheral blood cells of a patient with complete DiGeorge syndrome. Comparison of the sequences of 36 heavy chain clones to the recently expanded database of human VH genes permitted identification of the germline VH genes that are expressed in this patient as well as placement of 19 of these genes in a partially resolved 0.8-mb region of the human VH locus. The pattern of VH gene use does not resemble the fetal (early) repertoire. However, as in the fetal repertoire, there are a number of cDNAs derived from germline genes that previously have been identified as autoantibodies. Two D mu sequences also were identified, as was another sequence resulting from a unique recombination event linking JH to an unidentified sequence containing a recombination signal sequence-like heptamer. All of the DiGeorge cDNAs are closely related to germline VH genes, showing little or no evidence of somatic mutation. In contrast, comparably selected IgM VH sequences derived from normal adult and age-matched human libraries, and from a second DiGeorge syndrome patient in whom the degree of thymic dysfunction is much less severe, exhibit considerable evidence of somatic mutation. The absence of somatic mutation is consistent with the atypical development of functional antibody responses associated with complete DiGeorge syndrome and implicates a role for T cells in the generation of diversity within the B cell repertoire.

Transcriptional down-regulation of tumor necrosis factor-alpha gene expression by a synthetic peptide homologous to retroviral envelope protein

We have previously shown that a synthetic peptide (CKS-17) homologous to retroviral envelope protein suppresses the accumulation of superantigen staphylococcal enterotoxin-induced TNF-alpha mRNA in human PBMC and in highly purified human monocytes. The present study was designed to examine the underlying mechanism(s) by which CKS-17 down-regulates the TNF-alpha mRNA expression using a human acute monocytic leukemia cell line THP-1 stimulated with the superantigen staphylococcal enterotoxin E. A cyclooxygenase inhibitor indomethacin does not reverse the inhibition of TNF-alpha mRNA expression by CKS-17, suggesting that prostaglandins are not responsible for the suppressive action of CKS-17. The inhibitory effect of CKS-17 is, however, significantly blocked by a protein synthesis inhibitor cycloheximide, indicating that CKS-17 requires de novo protein synthesis to induce the suppressive activity. The mRNA stability assays using actinomycin D show that CKS-17 does not decrease the TNF-alpha mRNA stability. Nuclear run-on transcription assays further reveal that CKS-17 suppresses the TNF-alpha mRNA transcription rate. Taken together, these results suggest that the synthetic retroviral peptide CKS-17 down-regulates TNF-alpha mRNA expression through inhibition of transcriptional activation of the TNF-alpha gene, which requires de novo synthesis of a transcriptional repressor protein(s).

Development and characterization of monoclonal antiplatelet autoantibodies from autoimmune thrombocytopenic purpura-prone (NZW x BXSB)F1 mice

Male (NZW x BXSB)F1 (W/BF1) mice develop systemic autoimmunity involving autoantibodies, progressive thrombocytopenia, lupus nephritis, and degenerative coronary vascular disease with myocardial infarction. Platelet-associated IgG (PAIgG) on the platelet surface mediates platelet destruction by the reticuloendothelial system in the autoimmune thrombocytopenic purpura (ATP) of W/BF1 mice. Because the epitopes targeted in ATP by PAIgG have not been identifiable using serum from thrombocytopenic W/BF1 mice, we developed seven hybridomas secreting antiplatelet monoclonal antibodies (MoAbs) using splenocytes of thrombocytopenic W/BF1 mice. Epitopes recognized by three MoAbs were similar to those recognized by PAIgG, because eluted IgG from platelets of thrombocytopenic W/BF1 mice inhibited platelet binding by MoAbs in competitive micro-enzyme-linked immunosorbent assay. Hybridoma cells or purified Ig from the ascites of two clones (2A12 and 6A6), when injected into nude mice produced acute thrombocytopenia, elevated the levels of PAIgG, purpura, and megakaryocytosis. MoAbs of two clones also reacted with single-stranded DNA or double-stranded DNA, and one of these clones (4-13) bound to cardiolipin (CL) but was nonpathogenic in nude mice, suggesting that anti-CL and antiplatelet autoantibodies can be distinct. On immunoblotting analysis, antiplatelet MoAbs frequently bound a 100-Kd platelet protein. These MoAbs contribute to an understanding of the etiopathogenesis of ATP and the several antigens and autoantibodies involved.

Lymphohemopoietic reconstitution using wheat germ agglutinin-positive hemopoietic stem cell transplantation within but not across the major histocompatibility antigen barriers

Nonadherent (NA), low density (LD), wheat germ agglutinin-positive (WGA+) murine hemopoietic stem cell-enriched preparations (HSCPs) were tested for the capability to reconstitute lymphohemopoietic elements in lethally irradiated mice. HSCPs from BALB/c mice reconstituted lethally irradiated, major histocompatibility complex (MHC)-matched DBA/2 mice to normal histology of the thymus and spleen and normal humoral and cellular immune functions. By contrast, lethally irradiated B6 mice could not be reconstituted after transplantation with NA, LD, WGA+ cells from MHC-mismatched BALB/c mice. We previously observed frequent survival, stable chimerism, and normally vigorous functioning immune systems in B6 mice transplanted with T-cell-depleted bone marrow from both BALB/c and B6 donors. To extend these findings to a stem cell transplantation system, lethally irradiated B6 mice were transplanted with NA, LD, WGA+ cells from both BALB/c and B6 mice. These mixed stem cell-enriched preparations did not reconstitute the lethally irradiated, MHC-mismatched mice. By contrast, such HSCPs from BALB/c plus DBA/2 into DBA/2 mice reconstituted the hematologic and lymphoid tissues and functional immune systems when the donor and the recipient pairs were matched at MHC and mismatched at multiminor histocompatibility barriers. These purified blood progenitors thus appear to lack certain cells/factors essential for engraftment and reconstituting recipients in a fully allogeneic environment.

Lymphokine-activated killer cell activity of CD4-CD8- TCR alpha beta + thymocytes

Functions of CD4-8-TCR alpha beta+ thymocytes, which are characterized by predominant usage of V beta 8.2 TCR, have remained unclear. In this study, we found that the CD4-8-TCR alpha beta + thymocytes expressed NK1.1 Ag and IL-2R beta-chain but not IL-2R alpha-chain. When the CD4-8- TCR alpha beta + thymocytes were cultured in the presence of IL-2, the CD4-8-TCR alpha beta + thymocytes vigorously proliferated. After 7 days of culture in the presence of 1000 U/ml of IL-2, approximately half of the CD4-8-TCR alpha beta + thymocytes lost NK1.1 Ag. However, the remaining half of the CD4-8-TCR alpha beta + cells showed increasing levels of NK1.1 Ag and acquired killer activity against tumor cells such as YAC-1, P815, and EL-4. These cells also killed syngeneic as well as allogeneic thymocytes. The LAK activity by the NK1.1+ CD4-8-TCR alpha beta + thymocytes was not inhibited by anti-NK1.1, anti-TCR alpha beta, or anti-CD44 mAb but was partially inhibited by anti-LFA-1 mAb. These findings indicate that the CD4-8-TCR alpha beta + thymocyte population can be divided into two population on the basis of NK1.1 expression after culture in the presence of IL-2. The NK1.1 Ag expression on the cultured CD4-8-TCR alpha beta + seems to be correlated to acquisition of LAK activity, although the NK1.1 Ag itself may not be directly involved in the target cell recognition. The present data suggest that the CD4-8- TCR alpha beta + thymocyte population is a functional T cell lineage which may serve as cells of immune defense and/or immune regulation.

Lymphokine-activated killer cell activity of CD4-CD8- TCR alpha beta + thymocytes

Functions of CD4-8-TCR alpha beta+ thymocytes, which are characterized by predominant usage of V beta 8.2 TCR, have remained unclear. In this study, we found that the CD4-8-TCR alpha beta + thymocytes expressed NK1.1 Ag and IL-2R beta-chain but not IL-2R alpha-chain. When the CD4-8- TCR alpha beta + thymocytes were cultured in the presence of IL-2, the CD4-8-TCR alpha beta + thymocytes vigorously proliferated. After 7 days of culture in the presence of 1000 U/ml of IL-2, approximately half of the CD4-8-TCR alpha beta + thymocytes lost NK1.1 Ag. However, the remaining half of the CD4-8-TCR alpha beta + cells showed increasing levels of NK1.1 Ag and acquired killer activity against tumor cells such as YAC-1, P815, and EL-4. These cells also killed syngeneic as well as allogeneic thymocytes. The LAK activity by the NK1.1+ CD4-8-TCR alpha beta + thymocytes was not inhibited by anti-NK1.1, anti-TCR alpha beta, or anti-CD44 mAb but was partially inhibited by anti-LFA-1 mAb. These findings indicate that the CD4-8-TCR alpha beta + thymocyte population can be divided into two population on the basis of NK1.1 expression after culture in the presence of IL-2. The NK1.1 Ag expression on the cultured CD4-8-TCR alpha beta + seems to be correlated to acquisition of LAK activity, although the NK1.1 Ag itself may not be directly involved in the target cell recognition. The present data suggest that the CD4-8- TCR alpha beta + thymocyte population is a functional T cell lineage which may serve as cells of immune defense and/or immune regulation.

Generation of CD8+ suppressor T cells by protoscoleces of Echinococcus multilocularis in vitro

Addition of protoscoleces (PSC) of Echinococcus multiocularis suppressed proliferative responses in spleen cells stimulated with concanavalin A (Con A) on day 3 of culture. The suppression was not observed in the spleen cell population depleted of CD8+ cells but observed in the population depleted of CD4+ cells, suggesting the involvement of the CD8+ T cells in the apparent suppression. Indeed, flow cytometry analysis revealed that the proportion of CD8+ cells markedly increased in the Con A cultures containing PSC. Furthermore, when spleen cells were co-cultured with PSC alone, marked increase in the proportion of CD8+ cells as well as B220+ cells was observed. Addition of these increasing CD8+ cells suppressed the proliferative responses of fresh spleen cells stimulated with Con A. These findings suggest that the low responsiveness of spleen cells to Con A on day 3 of culture in the presence of PSC is attributable to an active suppressor mechanism including CD8+ T-suppressor cells generated by stimulation with PSC.

Molecular basis of a multiple lymphokine deficiency in a patient with severe combined immunodeficiency

We have previously reported that the T lymphocytes of a child with severe combined immunodeficiency are defective in the transcription of several lymphokine genes that include IL2, IL3, IL4, and IL5, which encode interleukins 2, 3, 4, and 5 (IL-2, -3, -4, and -5). To determine whether the defect in the patient's T lymphocytes involved a trans-acting factor common to the affected lymphokine genes, we examined the ability of nuclear factors from the patient's T lymphocytes to bind response elements present in the regulatory region of IL2. Nuclear factor NF-kB, activation protein 1 (AP-1), OCT-1, and NF-IL-2B binding activity were normal. In contrast, the binding of the nuclear factor of activated T cells (NF-AT) to its response element in the IL2 enhancer and to an NF-AT-like response element present in the IL4 enhancer was abnormal. To ascertain whether the abnormal NF-AT binding activity was related to an impaired function, we transfected patient and control T lymphocytes with constructs containing the reporter gene encoding chloramphenicol acetyl transferase (CAT) under the control of the entire IL2 regulatory region or of multimers of individual enhancer sequences. CAT expression directed by the IL2 regulatory region or by a multimer of the NF-AT-binding site was markedly lower in the patient relative to controls. In contrast, CAT gene expression directed by a multimer of the OCT-1 proximal (OCT-1p)-binding site was equivalent in patient and controls. These results indicate that an abnormality of/or influencing NF-AT may underlie the multiple lymphokine deficiency in this patient.

Genetic selection for crescent formation yields mouse strain with rapidly progressive glomerulonephritis and small vessel vasculitis

We have established a recombinant inbred strain of mouse named spontaneous crescentic glomerulonephritis-forming mouse/Kinjoh or SCG/Kj. Mice of this strain spontaneously develop rapidly progressive glomerulonephritis. This strain of mice was derived from (BXSB/Mp x MRL/Mp-lpr/lpr)F1 hybrid mice by brother x sister mating coupled with repeated histopathologic selection for breeding of mice whose parents had the highest frequency of crescent formation in the kidneys. In this strain of mice, nephritis appears earlier and is more rapidly progressive than in any other murine model of systemic lupus erythematosus. Histopathologically, the characteristic renal lesions in the mice of this strain express a most dramatic form of crescentic glomerulonephritis. The lesions in the kidneys show only slight fine granular immune deposits along the glomerular basement membrane associated with remarkable extraglomerular proliferation and hemorrhage in Bowman's space. Although selection was not based on vasculitis, mice of this strain also exhibit a high incidence of necrotizing vasculitis. These vascular lesions involve primarily small arteries and arterioles and many organs and tissues but spare the kidneys. Thus this form of vasculitis has been found to be correlated with the crescentic form of glomerulonephritis but not with lymphoid hyperplasia of the spleen. We conclude that, in this strain of mouse, the rapidly progressive glomerulonephritis is genetically restricted and that this genetic restriction is firmly linked to that responsible for the vasculitis.

Calories, parity, and prolactin influence mammary epithelial kinetics and differentiation and alter mouse mammary tumor risk

Reduced calorie intake (RCI) suppresses mouse mammary tumor virus (MMTV) transcription and reduces mammary tumor (MT) incidence in C3H/Ou mice. Since efficient retroviral expression requires cell division, we investigated whether the suppression of MMTV and MT by RCI reflects changes in mammary histogenesis and lowered epithelial kinetics. Prolactin (PRL) augments MMTV transcription. Since PRL levels may be lowered by RCI, we evaluated whether lowered PRL in ad libitum-fed mice alters mammary histogenesis and MT incidence in a manner comparable to RCI. Pregnancy augments MMTV transcription. Hence, we also determined the effect of parity on mammary histogenesis, kinetics, and MT risk. One hundred thirty-five C3H/Ou mice were fed ad libitum or a RCI level and separated into six experimental groups. Twenty ad libitum-fed mice were injected with a dopaminomimetic to lower PRL, and 20 RCI mice were engrafted with adenohypophyses to elevate PRL. Twenty-seven ad libitum-fed mice and twenty-eight RCI mice experienced a single parturition. RCI protected nulliparous (P = 0.0001) and parous mice (P = 0.005) from MT development. Reduced calories or lowered PRL with ad libitum feeding similarly influenced mammary histogenesis, kinetics and MT risk (P > 0.5). Mammary glands of RCI mice or of ad libitum-fed mice with lowered PRL were histologically comparable and principally ductular with a low DNA-labeling index (DNA-LI) (P < 0.001). In contrast, the parenchyma of ad libitum-fed mice or of RCI mice with elevated PRL had exuberant alveoli formation, an elevated DNA-LI (P < 0.001), and preneoplastic lesions. Parity did not change the elevated DNA-LI and MT risk of ad libitum-fed mice but increased the mammary DNA-LI (P < 0.001) and MT incidence (P = 0.01) of RCI mice. Prevention of mammary tumorigenesis in C3H/Ou mice by RCI may result from modulated serum PRL activity and reduced mammary epithelial kinetics which suppress MMTV transcription and minimize the risk of activating protooncogenes.

Interleukin-1-dependent mitogenic responses induced by protoscoleces of Echinococcus multilocularis in murine lymphocytes

Mitogenic effects of protoscoleces (PSCs) of Echinococcus multilocularis on murine lymphocytes were studied. Spleen cells from normal BALB/c mice showed significant proliferative responses when cocultured with PSCs. Proliferative responses were observed in both the T and B cell populations. The PSCs also stimulated cells of the macrophage/monocyte lineage to secrete interleukin-1 (IL-1). Depletion of plastic- and Sephadex G-10-adherent cells from the spleen cell population significantly reduced the proliferative responses to PSCs and the low responsiveness was restored by addition of plastic-adherent cells to these cultures. Furthermore, addition of anti-IL-1 serum to the spleen cell cultures stimulated with PSCs completely suppressed the proliferative responses. These findings demonstrate that the mitogenic effect of PSC on lymphocytes depends on IL-1 secreted by cells of macrophage/monocyte lineage.

Suppression of T-cell proliferation by CD8+ T cells induced in the presence of protoscolices of Echinococcus multilocularis in vitro

Immunoregulatory influences of protoscolices (PSC) of Echinococcus multilocularis on murine T-lymphocyte functions have been examined in an in vitro system. Proliferative responses of spleen cells stimulated with concanavalin A (ConA) or anti-CD3 monoclonal antibodies were depressed by the addition of PSC. In the presence of PSC, both interleukin-2 (IL-2) production and IL-2 receptor (IL-2R) expression by lymphocytes stimulated with ConA were significantly reduced. However, exogenous IL-2 reconstituted both the ConA-stimulated proliferative responses and IL-2R expression. These findings suggest that PSC of E. multilocularis can suppress lymphoid cell responses via influences on IL-2 production. Indeed, addition of CD(8+)-enriched cells from cultures stimulated with ConA plus PSC to fresh spleen cells showed marked suppression of the ConA responses. IL-2 production as well as IL-2R expression on the spleen cells so treated were suppressed. These findings reveal a suppressive immunologic function induced by E. multilocularis PSC that involves inhibition of IL-2 production and reduction of IL-2R expression. The PSC-induced CD8+ cells appear to play a key role in the suppressive regulation of host immune responses against E. multilocularis.

Preventive action of carotenoids on the development of lymphadenopathy and proteinuria in MRL-lpr/lpr mice

The chemopreventive action of carotenoids on proteinuria and lymphadenopathy were examined in autoimmune-prone MRL-lpr/lpr (MRL/l) mice. They were fed a synthetic full-fed diet (16-18 kcal/mouse/day) with supplementation of beta-carotene or astaxanthin (0.19 mumoles/mouse, 3 times a week), and the development of lymphadenopathy and proteinuria were examined. MRL/l mice fed a full-fed diet without the supplementation of carotenoids or those fed a calorie-restricted (CR) diet (10-11 kcal/mouse/day, 60% calorie intake of full-fed mice) were employed as controls. CR dramatically delayed the development of proteinuria and lymphadenopathy, as reported previously. Carotenoids also significantly delayed the onset of these symptoms in MRL/l mice fed a full-fed diet. Carotenoids were half as effective as CR and astaxanthin, a carotenoid without provitamin A activity, which appeared to exert more significant preventive actions than beta-carotene in delaying the development of these symptoms. Similar chemopreventive actions of carotenoids were also demonstrated in MRL/l mice fed a regular diet (Lab Chow). CR has been shown to augment IL-2 production and to decrease serum prolactin levels in this strain, which may be related to its dramatic preventive action of autoimmunity. However, carotenoids did not affect IL-2 production nor prolactin levels in full-fed MRL/l mice. The chemopreventive actions of carotenoids observed in autoimmune-prone MRL/l mice may be attributed to yet unknown mechanisms, apart from their provitamin A activity or oxygen-quenching activity.

NK1.1+ CD4+ CD8- thymocytes with specific lymphokine secretion

CD4+8- or CD4-8+ thymocytes have been regarded as direct progenitors of peripheral T cells. However, recently, we have found a novel NK1.1+ subpopulation with skewed T cell antigen receptor (TcR) V beta family among heat-stable antigen negative (HSA-) CD4+8- thymocytes. In the present study, we show that these NK1.1+ CD4+8- thymocytes, which represent a different lineage from the major NK1.1- CD4+8- thymocytes or CD4+ lymph node T cells, vigorously secrete interleukin (IL)-4 and interferon (IFN)-gamma upon stimulation with immobilized anti-TcR-alpha beta antibody. On the other hand, neither NK1.1- CD4+8- thymocytes nor CD4+ lymph node T cells produced substantial amounts of these lymphokines. A similar pattern of lymphokine secretion was observed with the NK1.1+ CD4+T cells obtained from bone marrow. The present findings elucidate the recent observations that HSA- CD4+8- thymocytes secrete a variety of lymphokines including IFN-gamma, IL-4, IL-5 and IL-10 before the CD4+8- thymocytes are exported from thymus. Our evidence indicates that NK1.1+ CD4+8- thymocytes are totally responsible for the specific lymphokine secretions observed in the HSA- CD4+8- thymocytes.

Human prolactin regulates transfected MMTV LTR-directed gene expression in a human breast-carcinoma cell line through synergistic interaction with steroid hormones

Prolactin plays a key role in the regulation and growth of mammary cells, and influences tumor promotion. We have shown that chronic energy restriction intake depresses prolactin levels, inhibits production of MMTV proviral DNA and proto-oncogene expression in mammary glands and prevents development of mammary tumors. Since the expression and proto-oncogene activation of MMTV are regulated by promoter/enhancer elements within its long terminal repeat (LTR), in the present study we used a chloramphenicol acetyl transferase (CAT) reporter gene system and gene transfection methods to study the effect of prolactin on MMTV LTR using a human ductal carcinoma cell line T47D stably or transiently transfected with a plasmid consisting of the LTR upstream of CAT gene. Human prolactin or dexamethasone induced, respectively, a 2-fold or 6-fold increase in CAT activity compared with background CAT activity in the absence of hormones. However, the combination of human prolactin and dexamethasone strongly enhanced (20-fold) induction of the LTR compared with the control. Human prolactin also showed a synergistic effect with progesterone on LTR induction. Both LTR and CAT genes needed to be linked for induction of CAT activity by prolactin and dexamethasone. Our results indicate that human prolactin can act synergistically with steroid hormones to regulate MMTV LTR-directed gene expression in transfected T47D cells.

Effects of calorie restriction on immunologic functions and development of autoimmune disease in NZB mice

Chronic energy (calorie) intake restriction (CEIR) prolonged life, inhibited autoimmune disease, and influenced immunologic and hematologic parameters in NZB mice. Abnormalities in numbers and proportions of T and B cells populations were corrected. Deficient responses to phytomitogens, mixed lymphocyte reactions, formation of plaque-forming cells to sheep red blood cells in vitro, production of cytotoxic T lymphocytes after in vitro stimulation, and interleukin 2 production were also corrected. CEIR prevented the extreme splenomegaly that normally occurs with age in NZB mice. This influence was associated with reduction of a greatly expanded non-T, non-B lymphoid cell population. Calorie restriction also prevented in NZB mice the rapid decrease in total numbers of colony-forming B cells in bone marrow that is also characteristic of mice of this strain. The influences of CEIR on immune parameters and hematopoiesis were generally less marked in non-autoimmune-prone DBA/2 mice than in autoimmune-prone NZB mice. CEIR has been shown to produce profound influences on several strains of autoimmune-prone mice (NZB x NZW)F1, MRL/lpr, BXSB, and NZB herein). In each of these strains, the pathogenesis and manifestations of autoimmune disease are dissimilar. Therefore, it seems likely that calorie restriction acts on an as yet elusive mechanism that operates to foster development of the diseases associated with aging common to each of these autoimmune strains as well as autoimmune-resistant mice and rats. Further investigation of the molecular and cellular bases of the benefits of CEIR seems urgent.

Effects of ultraviolet-inactivated feline leukemia virus on the production of alpha/beta interferon by feline peripheral blood mononuclear cells

The effects of ultraviolet-inactivated feline leukemia virus (UV-FeLV) on the production of alpha and/or beta interferon (IFN) by mononuclear cells stimulated with the Newcastle disease virus (IFN-NDV) was investigated. The production of IFN-NDV and gamma IFN was suppressed by 50% as compared to the control in the presence of 200 ng/ml or 200 micrograms/ml of UV-FeLV, respectively. The presence of UV-FeLV decreased the rate of the production, but the time to reach the plateau of the IFN activity in the culture supernatant was not shortened in both IFNs. It was suggested that the suppressive effects of UV-FeLV against both IFNs were through rather similar mechanisms. The suppressive effects of UV-FeLV on IFN-NDV production was most evident in the cultures to which UV-FeLV was added at the early stages of the culture, and could not be demonstrated when UV-FeLV was added 8 hr after initiation of the culture. These data therefore indicate that non-infectious feline leukemia viral particles can modify the production of feline IFNs by peripheral blood mononuclear cells.

Superantigen staphylococcal enterotoxin B-induced T-helper cell activation is independent of CD4 molecules and phosphatidylinositol hydrolysis

The role of the CD4 molecule in activation of T-helper cells was examined by investigating the effect of an anti-CD4 monoclonal antibody (Leu3a) in conventional peptide antigen-specific cloned T-helper cells that are also reactive to staphylococcal enterotoxin B (SEB). These T-helper cell clones are CD4+/CD45RO+/T-cell antigen receptor beta-chain variable region 12-positive and can respond to nominal peptide antigens and SEB by proliferation in the presence of class II major histocompatibility complex-expressing accessory cells. Although antigen and SEB were comparable in their ability to induce proliferative responses, interleukin 2 (IL-2) production, and IL-2 receptor alpha-chain expression, stimulation with SEB failed to trigger phosphatidylinositol hydrolysis or a rise in the intracellular free calcium ion concentration. Leu3a treatment inhibited antigen-induced proliferative responses of T cells with concomitant suppression of IL-2 production and IL-2 receptor expression. In contrast, SEB-induced responses were unaffected by Leu3a. These findings indicate that the functional consequences of binding (ligation) of conventional antigen and of superantigen with the T-cell receptor are distinct in the context of both signal transduction pathways and participation of CD4 molecules.

A strategy for making synthetic peptide vaccines

We have determined the H-2 class II allele-specific amino acid motif of the agretope (the site of contact between the peptide antigen and the major histocompatibility complex) for a synthetic peptide composed of residues 43-58 of pigeon cytochrome c (p43-58). Residues 46 and 54 functioned as the agretope, and residues 50 and 52 functioned as the epitope (the site for contact between the peptide antigen and the T-cell antigen receptor). In general, agretopes and epitopes function independently. Thus, substitution of amino acids in the epitope does not significantly affect binding of the peptide antigen to a class II molecule. On the basis of these findings, synthetic peptide vaccines against influenza Aichi (H3N2) virus were prepared by introducing seven residues of the influenza virus hemagglutinin into the frame component residues 43-46 and 54-58 of p43-58 analogues including the agretopes for Ak or Ab previously determined on the p43-58 segment. These peptide vaccines induced both helper T-cell responses and production of antibodies that were specific for influenza Aichi hemagglutinin but not for the major histocompatibility complex binding frame in mice bearing Ak or Ab. The antibodies produced neutralize the infectivity of influenza Aichi in vitro. The present findings should provide a basis for preparing potent peptide vaccines that function without producing side effects.

A synthetic peptide homologous to retroviral envelope protein down-regulates TNF-alpha and IFN-gamma mRNA expression

We investigated the influence of CKS-17, a synthetic heptadecapeptide that corresponds to a highly conserved domain of the immunosuppressive retroviral envelope protein p15E, on staphylococcal enterotoxin B (SEB)-induced TNF-alpha gene expression in human peripheral blood mononuclear cells and highly purified human monocyte preparations, as well as the production of TNF-alpha protein, using human peripheral blood mononuclear cells. RNA hybridization studies show that CKS-17 inhibits SEB-induced TNF-alpha mRNA accumulation in human peripheral blood mononuclear cells and human monocytes. CKS-17 is also shown to be highly suppressive for SEB-induced production of TNF-alpha proteins. Similarly, CKS-17 inhibits expression of SEB-induced IFN-gamma mRNA in human peripheral blood mononuclear cells. These results suggest that CKS-17 down-regulates both TNF-alpha and IFN-gamma production at mRNA level.

Effects of K-76COOH (MX-1) on immune response: induction of suppressor T-cells by MX-1

K-76COOH (MX-1), isolated from the cultured supernatant of a species of fungi imperfecti, Stachybotrys complement nov. sp. K-76, is an inhibitor of the complement component, C5. The effects of MX-1 on various immune responses were investigated. MX-1 enhanced the response of spleen cells to PHA and LPS: MX-1 at 0.01-250 micrograms/ml for PHA and at 10-250 micrograms/ml for LPS. In contrast, it inhibited the response to Con A: MX-1 at 0.01-500 micrograms/ml for spleen cells and at 100-500 micrograms/ml for thymocytes. MX-1 and IL-1 synergistically acted to enhance the Con A response of spleen and thymus cells from which accessory cells and Ia-positive cells had been removed by passing through Sephadex G-10 columns and treating with anti-Ia monoclonal antibody plus complement. T-cells pretreated with MX-1, IL-1 and Con A for 3 days suppressed not only the response of B-cells to LPS but also the production of anti-SRBC antibodies. In addition, MX-1 was found to increase CD8+ T-cells. These results suggest that MX-1 acts on T-cells to induce suppressor T-cells.

An NK1.1+ CD4+8- single-positive thymocyte subpopulation that expresses a highly skewed T-cell antigen receptor V beta family

In the present report we describe a CD4+8- heat stable antigen-negative (HSA-) thymocyte subpopulation that expresses a distinguishably low density of alpha beta T-cell antigen receptors (TCRlo) from the majority of CD4+8- high-density TCR (TCRhi) mature-type thymocytes. This subpopulation appears relatively late in life. Analysis of MEL-14, Pgp-1 (CD44), ICAM-1 (CD54), and NK1.1 expression on this subpopulation revealed that the CD4+8- TCRlo population was a population having unique characteristics (MEL-14-, CD44+, ICAM-1+, and NK1.1+) compared to the CD4+8- TCRhi thymocytes, most of which are MEL-14+, CD44-, ICAM-1-, and NK1.1-. When TCR beta-chain variable region (V beta) usage was analyzed, this thymic population expressed predominantly products of V beta 7 and V beta 8.2 TCR gene families. Interestingly, cells with V beta 8.1 TCRs, which are reactive to Mls-1a antigens, were not eliminated from the CD4+8- HSA- TCRlo subpopulation but had been eliminated from the major CD4+8- HSA- TCRhi subpopulation in Mls-1a strains. A subset with a phenotype similar to the CD4+8- HSA- TCRlo thymocytes was also identified primarily in bone marrow, and this subset constituted approximately half of the CD4+ T cells in the bone marrow. The CD4+8- HSA- TCRlo cells showed extremely high proliferative responses to immobilized anti-TCR antibody but generated negligible responses to allogeneic H-2 antigens compared to the responses generated by the major CD4+8- HSA- CD3hi cells. However, the CD4+8- HSA- TCRlo cells in Mls-1b mice mounted vigorous proliferative responses to Mls-1a antigens but not in Mls-1a mice. The properties of this T-cell subset suggest that these cells belong to a lineage distinct from the major T-cell population.

Improved enzyme immunosorbent assay for mouse prolactin using penicillinase as label

Enzyme immunosorbent assay (EIA) for mouse prolactin was established by modifying a method originally developed for human prolactin by Shrivastav et al. This simple, sensitive, rapid, and reproducible assay utilizes penicillinase as the labeling enzyme, rabbit anti-mouse prolactin antibody (Ab) and goat anti-rabbit Ig Ab as the first and second antibodies. Prolactin reference preparations and enzyme-conjugated prolactin were mixed with the first Ab and incubated for 0.5 h at 4 degrees C (24-48 h for serum samples). Then, the sample mixture was transferred to the wells of microtiter plate coated with the second Ab. After being kept at room temperature for 2 h, the plate was washed and filled with substrate solution (penicillin V). Absorbance at 620 nm was measured with an ELISA reader to quantitate the amount of conjugated prolactin bound to the second Ab. The prolactin levels obtained by this assay exhibited good correlation with those measured by radioimmunoassay (RIA) (y = 0.95x + 9.14, r = 0.943), and the sensitivity of EIA was equivalent to that of RIA (1.7 ng/ml). The CVs of intra-assay and inter-assay by EIA for mouse serum samples ranged comparably to those by RIA.

Disulfide-linked and non-disulfide-linked gamma/delta T-cell antigen receptors: differential expression on T-cell lines and clones derived from normal donors and patients with primary immunodeficiency disorders

We studied the expression of gamma delta T cell receptors (TCR) on T-cell lines and clones derived from peripheral blood lymphocytes (PBL) from certain patients with primary immunodeficiency disorders and normal donors. Immunoprecipitation with the anti-Leu 4, anti-gamma-chain and/or anti-delta-chain monoclonal antibodies followed by SDS-PAGE analysis revealed that 7 of 13 (54%) T-cell lines and clones developed from PBL of patients with primary immunodeficiency disorders expressed non-disulfide-linked gamma delta TCR, utilizing either the C gamma 2abc or the C gamma 2bc gamma-chain constant region gene segment. 5 of 13 (38%) T-cell lines/clones expressed disulfide-linked gamma delta TCR, whereas an additional T-cell line was comprised of T cells expressing either disulfide-linked (C gamma 1) or non-disulfide-linked (C gamma 2bc) gamma delta TCR. T-cell lines and clones developed from four of light patients with primary immunodeficiency disorders exhibited exclusively non-disulfide-linked gamma delta TCR utilizing either the C gamma 2abc or the C gamma 2bc gamma-chain segment. T-cell lines derived from a fifth patient exhibited primarily non-disulfide-linked gamma delta TCR, bringing to five of eight the numbers of patients that expressed exclusively or primarily non-disulfide-linked gamma delta TCR. T-cell lines/clones derived from the remaining three patients exhibited exclusively disulfide-linked gamma delta TCR. The age of these patients varied over a wide range and there was not an association between their age and the type of gamma delta TCR expressed on T-cell lines derived from their PBL. In contrast, to these findings 14 of 16 (87.5%) T-cell clones derived from PBL of normal donors expressed disulfide-linked gamma delta TCR, whereas only 2 of 16 (12.5% expressed non-disulfide linked gamma delta TCR. Among the T-cell clones from normal donors which express disulfide-linked gamma delta TCR two different types were identified. Those exhibiting under reducing conditions on SDS-PAGE two completely resolved polypeptide chains in the range of 37 kD to 44 kD, and those exhibiting under the same conditions indistinguishable overlapping gamma- and delta- chains in the range of 40-42 kD. Several T-cell lines and clones from normal donors or patients with primary immunodeficiency that expressed either disulfide- or non-disulfide-linked gamma delta TCR were delta TCS1+, demonstrating that the delta TCS1 determinant is expressed on both types of gamma delta TCR.(ABSTRACT TRUNCATED AT 400 WORDS)

Influence of calorie restriction on oncogene expression and DNA synthesis during liver regeneration

Controlling calorie intake (CCI) extends healthful life-span by a mechanism that may involve reduced rates of cell division without detriment to inducible cellular responses. To test whether inducible cellular proliferation is preserved by CCI and whether the mRNA expression levels of oncogenes activated by cell division can be reduced by CCI, we evaluated the effect of dietary energy on the hepatocellular proliferative burst and on oncogene and growth factor mRNA expression induced by partial hepatectomy. Eighty Fischer 344 rats were separated into two dietary groups and were fed semipurified diets for 10 weeks that differed only in calories by 40%. Mean hepatic levels of [3H]thymidine incorporation were greater among CCI animals at 18, 24, 28, and 36 hr after partial hepatectomy. The expression of c-fos and c-Ki-ras mRNAs, activated during hepatic regeneration, was reduced by CCI. Peak expression of c-fos among ad libitum fed controls to levels 4-6 times greater than prehepatectomy levels was not detected among CCI animals. Protracted elevated expression of c-Ki-ras among ad libitum fed animals was foreshortened by CCI. These findings demonstrate that inducible cellular proliferative responses are preserved by CCI and that the mRNA expression levels of c-fos and c-Ki-ras activated during cell division are reduced by controlling dietary energy. Preserved inducible cellular responses and lowered oncogene expression during cell division may be attributes of the healthful protective effect of CCI.

Development and characterization of monoclonal antibodies to lymphocyte cell surface antigens of the rhesus monkey

Three monoclonal antibodies directed against rhesus lymphocyte cell surface antigens are described. A pan-T mAb, T64, and a T suppressor mAb, T35, showed phenotypic and functional specificity for both human and rhesus cells. In contrast, a third mAb, N42, identifying natural killer cells in rhesus peripheral blood leukocytes, was not crossreactive with the corresponding homologous human cells. N42 reacted with the same cells identified by Leu 11a and Leu 11b in rhesus PBL and in a functional assay decreased NK activity by 80%. N42 precipitated a 50KD protein from rhesus PBL lysates and was reactive with the Fc receptor domain of the NK cell. The T-S functional activity of cells reactive with mAb T35 was demonstrated in a pokeweed-mitogen-driven system for Ig synthesis: removal of the T35 positive cells by complement-mediated lysis led to an enhanced production of Ig by rhesus PBL, and the addition of T35 positive cells to a culture of T helper and B cells resulted in a reduction of this response. T35 was determined to be an IgG2a immunoglobulin and precipitated a 34KD protein from rhesus cell lysates. An IgM immunoglobulin, mAb T64 delineated all T lymphocytes, inhibited E-rosette formation, interfered with the proliferation of cells stimulated with mitogens, and precipitated a 52KD membrane protein. The potential utilization of these mAbs in vivo for organ or tissue transplantation in the rhesus monkey is discussed.

Functional evaluation of T helper, T suppressor, and B lymphocytes in lethally irradiated rhesus monkeys injected with autologous bone marrow

Lethally irradiated rhesus monkeys were treated with autologous bone marrow that had either been (1) nontreated, i.e., normal; (2) depleted of T lymphocytes with a monoclonal antibody directed against rhesus T lymphocytes; (3) fractionated with the soybean agglutinin (SBA- fraction); or (4) fractionated with SBA and further depleted of T cells by E-rosetting. There was no difference in hematologic reconstitution among the animals, but all showed a marked lowering of the T helper/T suppressor ratio during the first 10 months posttransplant and reduced capability of their peripheral blood leukocytes (PBL) to produce Ig upon stimulation with pokeweed mitogen. This subnormal ability of PBL to produce Ig, as measured by plaque-forming cells in a reverse hemolytic plaque assay, was not explained entirely by the altered T-H/T-S ratio but was correlated with the functional status of the T-H, T-S, and B lymphocytes. Isolated populations of the different lymphocyte subsets from PBL of the experimental animals were cocultured with normal cells of the appropriate subset to obtain Ig synthesis when stimulated with PWM. Animals treated with normal bone marrow showed recovery of T-H cell function after 5 months, but their T-S cells showed excessive suppressor activity that persisted for 20 months posttransplant. In contrast, those animals receiving treated marrow (mAb plus complement, or SBA) showed a much-delayed (12 months or more) return to normal T-H cell function and an earlier return of T-S cells expressing a normal level of suppressor activity. Since the SBA- fraction of marrow contains very few or no T-H cells and T cell depletion of marrow with mAb also removes these cells, it is suggested that the kinetics of immune recovery of the different lymphocyte subsets of PBL is influenced by the presence or absence of T-H cells in the marrow inocula.

The effects of dietary restriction on immune function and development of autoimmune disease in BXSB mice

Chronic energy intake restriction (CEIR) prolonged the median life span and inhibited autoimmunity and development of autoimmune disease in BXSB mice, as has been established for mice of several other autoimmune-prone, short-lived strains. Whether imposed just after weaning or delayed until manifestations of disease had appeared, CEIR inhibited or reversed development of autoimmunity and immune complex-based renal disease in male BXSB mice. CEIR also prevented the formation of anti-DNA antibodies and prevented the increase in circulating immune complex levels that is typically observed in male mice of this strain. Moreover, CEIR inhibited development of splenomegaly and prevented the normal age-associated decline of a number of immunological functions, including interleukin 2 production, cell-mediated cytotoxic responses, and mixed lymphocyte reactivity. The observed improvement in cell-mediated immune responses was attributed largely to the capacity of CEIR to inhibit development of the splenomegaly that occurs concomitant with expansion of a non-T, non-B lymphoid cell population. These findings emphasize that CEIR, even when imposed relatively late in life in BXSB mice, can influence expression of autoimmunities and autoimmune diseases of different genetic origins and presumed pathogenetic bases.

Suppression of human interferon-gamma production by a 17 amino acid peptide homologous to the transmembrane envelope protein of retroviruses: evidence for a primary role played by monocytes

CKS-17, a synthetic amino acid peptide homologous to a highly conserved region of retroviral transmembrane protein exerts a suppressive action on staphylococcal enterotoxin A (SEA)-induced the production of IFN-gamma by human peripheral blood mononuclear cells (PBMC) (Ogasawara et al., J. Immunol. 141, 615, 1988). This action has been shown in the present study to be preceded by dramatic clustering of PBMC. Clusters appear within 3 hr of exposure of PBMC to CKS-17; they are dose dependent, inhibited by cycloheximide, and require a temperature of 37 degrees C. The cells in the clusters are predominantly monocytes. Although it has been previously shown that CKS-17 inhibits monocyte-mediated killing by inactivating IL-1 (Kleinerman et al., J. Immunol. 139, 2329, 1987) and production of IL-2 by murine thymoma cells treated with IL-1 (Gottlieb et al., J. Immunol. 142, 4321, 1989), in the present study we show that IL-1 does not prevent clustering of PBMC by CKS-17. Using CKS-17 and highly purified monocytes or lymphocytes, profound alterations occur only with monocytes, as revealed by light or electron microscopy. SEA- or staphylococcal enterotoxin B-induced production of IFN-gamma is inhibited when highly purified monocytes pretreated with CKS-17 are cocultured with highly purified T lymphocytes. Thus, CKS-17 induces dramatic clustering of cells apparently by inducing alterations of monocytes but not lymphocytes, suggesting that CKS-17 may interfere with the capacity of monocytes to facilitate production of IFN-gamma by T lymphocytes.

RNA/nucleotide enhances antibody production in vitro and is moderately mitogenic to murine spleen lymphocytes

Suppression of immune functions was demonstrated in both humans and animals when exogenous RNA was eliminated from the diet. However, direct actions of RNA/nucleotide on the immune system are virtually unknown. Thus, in this study, we explored effects of RNA and nucleotide on lymphocyte functions in vitro. Yeast whole RNA, which is free of endotoxin, was supplemented to culture media, and changes in mitogen responses, thymocyte proliferation, or in vitro antibody production by murine spleen lymphocytes were analyzed. Yeast whole RNA potentiated the proliferation of spleen lymphocytes and it also strikingly enhanced in vitro antibody production in response to sheep red blood cells at least 10-fold. However, it did not potentiate the proliferation of thymocytes (immature lymphocytes). These enhancing activities of yeast RNA were significantly reduced by RNAse treatment, but not by treatments with DNAse or polymyxin B. Certain mononucleotides exhibited less, but similar, action on murine spleen lymphocytes. The whole yeast RNA employed was already degraded to small nucleotide (less than 1 kb). Therefore, it may be suggested that certain components of RNA degraders can function as powerful immunomodulators, indicating that exogenous RNA or nucleotide may be important in facilitating immune responses under certain circumstances.

Nutrition and cellular immunity

We have investigated the influence of nutrition on immune function in animals and man over the past two decades. The profound impairment of immune function that had not been observed in children in developing countries could not consistently be reproduced in the laboratory setting; paradoxically, moderate nutritional restriction could even enhance T-cell-based cell-mediated immune responses in experimental animals. Studies of the crucial role of the element zinc in maintenance of vigorous cellular immunity provided at least a partial explanation of this paradox. Zinc, shown to be absolutely crucial for development and expression of both T- and B-cell functions, was commonly deficient as were other micronutrients under many conditions of protein-calorie malnutrition. Indeed, administration of adequate zinc alone could correct some of the T-cell-mediated immune functions in children with protein-calorie malnutrition. In later investigations we found that as long as all essential nutrients were supplied in adequate amounts, 40% chronic energy (calorie) restriction will regularly extend lifespan and maintain vigorous immunologic function while preventing numerous cancers and immunologically based diseases of aging, such as profound and destructive autoimmune diseases in genetically short-lived mice strains, as it was known to do for moderately long-lived rats and long-lived strains of mice. Such undernutrition without malnutrition appears to influence a wide range of critical metabolic and physiologic processes in both short-lived and long-lived animals. One of the most challenging of these influences was a down-regulation of cellular proliferation and cell turnover in each of the rapidly replicating tissues studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Induction of heat shock protein closely correlates with protection against Toxoplasma gondii infection

Heat shock proteins (HSPs) are evolutionarily highly conserved polypeptides that appear to be produced by many cells to preserve cellular functions under a variety of conditions of stress, including infections. We report that a 65-kDa HSP is present in mouse peritoneal cells that have been infected with a low-virulence (Beverley) strain of Toxoplasma gondii, as determined by electroblot assay using a monoclonal antibody specific for microbial HSP65. This HSP is, however, not expressed when infection occurs with the high-virulence RH strain of T. gondii. Furthermore, HSP was demonstrable in mice that acquired resistance against infection with a lethal dose of bradyzoites of the Beverley strain or even of an inoculum of a highly virulent strain of T. gondii (RH). From these results, it can be suggested that HSPs play an important role in developing effective defenses that include effective immune responses against infection with Toxoplasma parasites in vivo.

Enrichment of murine bone marrow natural suppressor activity in the fraction of hematopoietic progenitors with interleukin 3 receptor-associated antigen

Natural suppressor (NS) activity has been identified in several sites of active hematopoiesis. In this study we characterized NS activity in murine bone marrow (BM) using monoclonal antibodies (mAbs) to interleukin 3 (IL-3) receptor-associated antigen (IL-3RAA) and various cytokines that exert a strong influence on hematopoiesis or lymphocyte interaction. NS activity of BM cells of relatively low density was enhanced by IL-3 or granulocyte-macrophage colony-stimulating factor (GM-CSF). When the BM cells were separated into IL-3RAA+ cells and IL-3RAA- cells, the IL-3RAA+ cells demonstrated potent NS activity, whereas IL-3RAA- cells had either no or weak NS activity. The IL-3RAA+ cells showed non-T- and non-B-cell phenotype and had high affinity to wheat germ agglutinin (WGA), a marker for hematopoietic progenitors. In assays for hematopoietic activity, it appeared that the early differentiating progenitors (day 8 spleen colony-forming units [CFU-S], granulocyte-macrophage colony-forming units [CFU-GM]) were enriched in the IL-3RAA+ cell population, whereas more immature multipotent progenitors (day 12 CFU-S, granulocyte erythrocyte macrophage megakaryocyte colony-forming units [CFU-GEMM]) were contained in the IL-3RAA- cell population. Both suppressor cells and IL-3RAA+ cells spontaneously developed from the IL-3RAA- cell population. These findings suggest that NS cells in murine BM are early hematopoietic progenitors and are probably committed to the myeloid lineage. Hybridoma cells established between the IL-3RAA+ cells and BW5147 cells produced suppressor factor(s). This finding suggests that the NS cells produce soluble mediator(s) that may be responsible for their suppressive action.

Clonal elimination of self reactive V beta 6+ T cells induced by H-2 products expressed on thymic radio-resistant components

The role of thymic radio-resistant cells on clonal elimination of V beta 6+ T cells that are reactive to minor lymphocyte stimulatory (Mls)-1a plus I-E antigens has been investigated. Previous studies with allogeneic bone marrow chimeras revealed that radio-sensitive I-E+ cells derived from donor bone marrow in the thymus play a major role in the clonal elimination of V beta 6+ T cells. However, we could show that not only the thymic bone marrow derived components but also the radio-resistant ones (presumably thymic epithelial cells) might be involved in induction of clonal elimination of the self-reactive T cells. The proportion of V beta 6+ T cells present varied with the H-2 haplotype of the thymus and the cell types presenting Mls-1a products, which might be attributable to differences in the affinity of the H-2 products to T cell antigen receptors and differences in the amount of tolerogens expressed on the stromal cells.

Ethanol calories do not enhance breast cancer in isocalorically fed C3H/Ou mice

Mammary tumorigenesis is augmented when C3H/Ou mice are fed diet ad libitum but delayed when calories are restricted by 40%. Three feeding experiments were done to evaluate the effect of ethanol on mammary tumorigenesis in isocalorically fed C3H/Ou mice: 1) ad libitum feeding of semipurified solid diet, with one group receiving 12% ethanol (15 g/kg/day) in the drinking water while controls received water alone; 2) isocaloric pair feeding of semipurified solid diet, with ethanol (4 g/kg/day) administered by gavage five time per week; and 3) isocaloric pair feeding of Lieber-DeCarli liquid diet, with one group receiving 29% of calories as ethanol (20 g/kg/day) in the diet. Despite administration of ethanol to isocalorically fed C3H/Ou mice for 65 weeks by three different methods, mammary tumor development was not enhanced. In two of the three ethanol-consuming groups, weight gain and mean body weight were less in the ethanol-consuming mice than in the controls, despite equal total calorie consumption. In only one ethanol-consuming group, where mice received ethanol as a 12% solution in the drinking water, was any difference noted in the tendency to develop mammary tumors. In this case, delay in tumorigenesis was apparent in the ethanol-consuming animals (p = 0.03). These findings do not support the hypothesis that ethanol calories augment the risk of breast tumorigenesis among breast cancer-prone mice consuming isocaloric diets. Instead, reductions in weight gain and body weight among ethanol-consuming mice and an apparent reduction in mammary tumorigenesis in one of three experimental groups suggest that ethanol may decrease metabolic utilization of calories and hence contribute to lowered energy availability.(ABSTRACT TRUNCATED AT 250 WORDS)

Calorie restriction suppresses subgenomic mink cytopathic focus-forming murine leukemia virus transcription and frequency of genomic expression while impairing lymphoma formation

Calorie restriction suppresses mammary proviral mRNA expression and protooncogene activation in breast tumor-prone C3H/Ou mice while inhibiting tumor formation. To determine whether the beneficial effects of chronic energy-intake restriction (CEIR) can be extended to an organ site of retrovirus-induced tumorigenesis where the dynamics of growth and sexual maturity are not paramount as they are in breast tissue, calorie restriction of 40% was imposed on thymic lymphoma-prone AKR mice when 4 weeks old. Recombination between various murine leukemia virus (MuLV) mRNAs, resulting in the generation of an 8.4-kilobase genomic-length transcript with mink cytopathic focus-forming (MCF) characteristics, is considered the proximal retroviral event in AKR lymphomagenesis. Thymic expression of subgenomic MCF MuLV mRNA was uniformly suppressed among 6- and 8-week-old CEIR mice (P less than 0.02). This suppression of MuLV transcription preceded a 25% reduction in the appearance of genomic-length MCF transcripts among CEIR mice and a 28% reduction in cumulative lymphoma mortality. The latency to median tumor incidence was extended greater than 3 months by calorie restriction, and median lifespan was extended approximately 50%. Survival curves for the full-fed and CEIR dietary cohorts were found to be significantly different (P less than 0.0001), with full-fed mice experiencing a 3 times greater risk of lymphoma mortality. These findings extend the known range of pathologic states influenced by CEIR in inbred mice and show that retroviral mechanisms involved in generation of lymphoid malignancy can be significantly impaired by calorie restriction.

Zinc depletion modifies CD5 expression by 70Z/3 murine pre-B leukemia cell line

CD5 expression on B cells is regulated by certain humoral factors. In a pre-B leukemia cell line 70Z/3, we found that interleukin 4 down-regulates it. Herein, we report that zinc influences spontaneous CD5 expression by this cell line as well as actions of these factors on CD5 expression considerably. In zinc-depleted culture media, spontaneous CD5 expression by 70Z/3 cells was enhanced. In contrast, the down-regulatory action of interleukin 4 was significantly reduced under culture conditions of zinc depletion. The supplementation of zinc to physiologic concentrations (1 to 2 microM) abolished such effects of zinc-depleted medium. The reduction of the suppressive action of interleukin 4 was observed at the level of gene expression. However, CD5 mRNA expression enhanced by lipopolysaccharide or NZB-SF was not further enhanced under conditions of zinc deficiency. These observations may suggest that CD5 expression by malignant or even normal B cells may be influenced by cellular/serum zinc levels.

Intravenous immunoglobulin therapy for chronic inflammatory demyelinating polyneuropathy recalcitrant to conventional therapy

Chronic idiopathic demyelinating polyneuropathy is an immunologically mediated disorder that may not respond to glucocorticoid therapy, cytotoxic or other immunosuppressive medications, or plasmapheresis. We have reported such a case in which the patient had sustained clinical improvement with the repeated administration of high doses of intravenous immunoglobulin.

Long-term immunologic tolerance induction in chimeric mice after bone marrow transplantation across major histocompatibility barriers: persistent or redeveloping immunologic responsiveness after prolonged survival

Employing allogeneic bone marrow chimeras [B6----C3H] (C3H/HeN mice lethally irradiated and then reconstituted with T cell-depleted C57BL/6J bone marrow), we investigated the kinetics of immunological reconstitution and the functional characteristics of the immune system at regular intervals following bone marrow transplantation (BMT). In chimeric mice, almost all spleen cells and peritoneal macrophages showed donor H-2 haplotype within 2 weeks after BMT. The differentiation and maturation of B lymphocytes and macrophages was largely complete by 2 weeks following BMT, whereas T cell functions such as Con A responsiveness and alloreactivity were not restored within 4 weeks. Newly developed T cells were found to be exclusively of donor origin but were tolerant of both donor type and host type major histocompatibility complex (MHC) determinants in assays of mixed lymphocyte reactions and capacity to generate cytotoxic T lymphocytes. Fully allogeneic chimeric mice survived up to one year after bone marrow transplantation without significant reactions or serious diseases. Neither graft-versus-host reaction (GVHR), host-versus-graft reaction (HVGR), nor the wasting diseases described. As compared to age-matched control mice, such fully allogeneic chimeras exhibited one year following BMT somewhat reduced but quite significant plaque forming cell responses to in vitro stimulation with a T-dependent antigen, SRBC. These findings suggest that BMT across MHC barriers may ultimately be useful in humans if all manifestations of GVHR are eliminated by completely removing all T cells from the bone marrow and if all hematopoietic resistance and all aspects of HVGR are eliminated by using sufficient immunosuppression and myeloablation.

T-cell depletion of HLA-identical transplants in leukemia

We analyzed the effects of T-cell depletion on the outcome of HLA-identical sibling bone marrow transplants for leukemia by comparing 731 T-cell-depleted transplants with 2,480 non-T-cell-depleted transplants. T-cell depletion decreased acute graft-versus-host disease (GVHD) (relative risk [RR] 0.45; P less than .0001) and chronic (GVHD) (RR 0.56; P less than .0001). However, it increased graft failure (RR 9.29; P less than .0001). Leukemia relapse also was increased. In first remission acute leukemia or chronic phase chronic myelogenous leukemia, leukemia relapse was 2.75 times more likely after T-cell-depleted transplants (P less than .0001). T-cell depletion increased the risk of treatment failure (RR 1.35; P less than .0003) and decreased leukemia-free survival. We also studied controllable variables associated with outcome of T-cell-depleted transplants. The unique findings were that among recipients of T-cell-depleted transplants for early leukemia, radiation doses greater than or equal to 11 Gy (RR 0.54; P less than .01), dose rates greater than 14 cGy/min (RR 0.56; P less than .002), and additional posttransplant immune suppression with cyclosporine alone (RR 0.53; P less than .0006) or cyclosporine plus methotrexate (RR 0.36; P less than .01) were associated with fewer treatment failures. Use of monoclonal antibodies rather than physical techniques for T-cell depletion (RR 2.01; P less than .03) and fractionated radiation (RR 1.69; P less than .05) were associated with increased treatment failure and lower leukemia-free survival. These data may be useful in designing strategies to improve results of T-cell-depleted transplants.