A comparison of cyclosporine A and Nva2-cyclosporine (cyclosporine G) in a rat renal allograft model

We compared CsG and CsA in the DA-to-Lewis rat renal allograft model. At equivalent oral doses, plasma radioimmunoassay (RIA) CsG levels were higher than CsA (P less than 0.02). Neither drug prevented rejection at doses of 5 mg/kg/day. CsG-treated rats had a higher rejection rate at doses of 7.5 mg/kg/day (P less than 0.05). Both drugs were equally effective in preventing rejection at doses of 10 mg/kg/day. Neither drug was nephrotoxic at the doses used in this study. CsG is a potent immunosuppressant, and thus a potential clinical successor to CsA. Since CsG and CsA provide equivalent immunosuppression at therapeutic doses, CsG's clinical significance will ultimately depend on its nephrotoxicity in man.

Interleukin 1 and myelin basic protein synergistically augment adoptive transfer activity of lymphocytes mediating experimental autoimmune encephalomyelitis in Lewis rats

This investigation focused on the role of adherent accessory cells and their cellular product, interleukin 1 (IL 1), in cellular immune responses associated with experimental autoimmune encephalomyelitis (EAE) in Lewis rats. Guinea pig myelin basic protein (GPMBP)-sensitized lymph node cells (LNC) responded in culture with GPMBP by undergoing activation as measured by augmented transfer of EAE to syngeneic recipients, and proliferation as measured by [3H]thymidine incorporation. GPMBP-sensitized LNC, after depletion of adherent accessory cells, no longer responded to GPMBP in the EAE transfer activation assay. In contrast, aliquots of the same LNC preparation exhibited proliferative responses to GPMBP that were only partially reduced. Addition of irradiated thymocytes to adherent cell-depleted cultures fully reconstituted responsiveness to GPMBP in the activation assay and restored full reactivity to GPMBP in the proliferation assay. Furthermore, addition of either purified human IL 1 or recombinant human IL 1 to adherent cell-depleted cultures reconstituted reactivity to GPMBP in the EAE transfer activation assay and augmented GPMBP-specific proliferative responses. Anti-Ia monoclonal antibodies blocked GPMBP + IL 1-induced cellular activation of nonadherent LNC. These results demonstrate that both IL 1 and Ia molecules are important in the pathway leading to GPMBP-induced activation of EAE-inducing T lymphocytes. Furthermore, these results suggest that different accessory signals may be required for optimal induction of GPMBP-induced lymphocyte activation vs GPMBP-specific proliferative responses.

Donor-specific antigen and cyclosporine in rat islet allografts

Combination therapy with one dose of 3 M KCl extracted donor-soluble antigen (Ag) and a short course of cyclosporine (CsA) has proven to prolong the survival of kidney allografts by enhancing specific T-suppressor populations. This regimen is tested in rat islet allografts in this study (Lewis to ACI). A 3-day perioperative course of 10 mg/kg/day CsA on Days -1, 0, and 1 did not prolong graft survival (MST = 10.7 +/- 2.5 days vs 9.4 +/- 1.2 days in controls). When this course of CsA therapy was combined with a single dose of donor antigen on Day -1, the survival time was prolonged slightly but significantly (MST = 14.0 +/- 5.8 days). Three cycles of a 3-day course of CsA therapy at 7-day intervals, a total of nine doses of 10 mg/kg/day CsA, were effective in delaying rejection of islet allografts (MST = 26.4 +/- 30.3). Moreover, combined therapy with donor antigen and three cycles of a 3-day course of CsA prolonged the survival of islet allografts (MST = 57.7 +/- 51.4 days) with 50% of recipients still normoglycemic at 60 days after transplantation. These findings indicate that the combination therapy of donor antigen with a short course of CsA has a powerful effect to prevent the rejection of islet allografts, as shown in kidney allografts, in rats.

Specific vs. nonspecific immune responses in murine respiratory mycoplasmosis

Murine respiratory mycoplasmosis (MRM), due to Mycoplasma pulmonis, is a chronic respiratory disease in laboratory rats. LEW and F344 rats differ in the severity and progression of disease. LEW rats develop more severe disease than do F344 rats. Also, F344 rats are able to resolve lung and middle ear lesions, but the severity of these lesions in LEW rats continues to increase. LEW lymphocytes produce higher responses in vitro to various mitogens, including M. pulmonis mitogen, than do F344 lymphocytes; this difference is apparently due to higher levels of T-helper cells in LEW rats. The level of infiltration or expansion of mononuclear cells in the submucosa probably depends upon the host's ability to respond to nonspecific stimuli. In contrast to nonspecific responses, F344 rats produce a much higher specific antibody and cellular response to M. pulmonis antigens after immunization, suggesting that F344 rats, in contrast to LEW rats, are able to resolve lesions because they are able to mount an effective immune response to M. pulmonis.

Experimental autoimmune uveoretinitis (EAU) induced by retinal interphotoreceptor retinoid-binding protein (IRBP): differences between EAU induced by IRBP and by S-antigen

Rats immunized with the retinal interphotoreceptor retinoid-binding protein (IRBP) develop an inflammatory eye disease, "experimental autoimmune uveoretinitis" (EAU). The ocular changes which characterize the EAU induced by IRBP resemble those seen in rats which develop EAU by immunization with another retinal protein, S-antigen (S-Ag). Yet, the two antigens do not cross-react antigenically and the two diseases differ by several features: At low doses (less than or equal to 4 micrograms/rat), IRBP was more uveitogenic in Lewis rats than was S-Ag, inducing disease more reproducibly and with earlier onset time. On the other hand, at higher doses (greater than or equal to 20 micrograms/rat) the disease induced by S-Ag was more severe than that induced by the same doses of IRBP. Rats of various inbred strains differed in their susceptibility to EAU induced by these two antigens. In particular, BN rats were more susceptible to IRBP-induced EAU than to the S-Ag-induced disease, while WF and RCS-rdy+ rats developed severe EAU when immunized with S-Ag but showed minimal or no ocular change when immunized with IRBP.

Functional maturation of murine B lymphocyte precursors. II. Analysis of cells required from the bone marrow microenvironment

The development of mature B cells in cultures of early B cell precursors depends on the presence of a confluent adherent bone marrow (aBM) cell layer. Adherent and sIgM+ cell-depleted bone marrow (BM) from untreated or 5-fluorouracil-pretreated donors or day 12 fetal liver cells were used as precursor cell populations. When adherent cells from thymus or highly enriched BM-derived macrophages were co-cultured with precursor cells, mature B cells were not developed. Similarly, aBM cell layers generated in the presence of hydrocortisone and horse serum were unable to support aBM cell-dependent precursor differentiation, even though cortisone was removed before the addition of precursor cells. In contrast, this type of microenvironment promoted the differentiation of precursor of myeloid cell lineages. Repeated treatment of established aBM cell populations with a monoclonal anti-macrophage antibody (31.3, known to recognize a surface marker on a subset of BM macrophages) and complement abolished the capacity of otherwise functional aBM cells to sustain the development of B cell precursors. Macrophage-depleted aBM cells regained their function after supplementation with highly enriched BM-derived macrophages grown in vitro. Limiting dilution analysis of aBM cells in microcultures containing saturating numbers of early B cell progenitors also suggests the participation of more than one cell type in the BM cell population. In conclusion, differentiation of early B cell progenitors requires macrophages in addition to at least one additional cell type contained in the aBM cell population.

Serum antibody and cellular responses in LEW and F344 rats after immunization with Mycoplasma pulmonis antigens

Mycoplasma pulmonis causes a chronic respiratory disease in rats which is more severe in LEW than in F344 rats. This study compared the ability of each of these rat strains to produce specific immune responses to M. pulmonis antigens. By an enzyme-linked immunosorbent assay, LEW rats were found to produce approximately 10 times lower levels of specific immunoglobulin G (IgG) after immunization with M. pulmonis antigens than F344 rats, while no significant difference was found in the levels of IgM. The difference in IgG levels was due to much greater levels of specific IgG2b (about 50 times) in F344 rats; no differences were found in other subclasses. Nonimmune LEW rats were found to have as much total IgG2b in their sera as unimmunized F344 rats by a single radial immunodiffusion test; thus, the difference was not due to the inability of LEW rats to produce IgG2b. In contrast to the antibody response to M. pulmonis antigens, anti-keyhole limpet hemocyanin IgG responses in LEW and F344 rats were similar, but F344 rats produced significantly more (about 21 times) IgG2b than was found in M. pulmonis responses. Antisera from F344 rats recognized several additional M. pulmonis antigens than antisera from LEW rats; however, this could not explain the differences in the level of IgG2b in LEW and F344 rats. In vitro stimulation of splenic lymphocytes with M. pulmonis antigens from immunized F344 rats produced much greater proliferative responses than in LEW and nonimmune F344 cells. Thus, the susceptible rat strain LEW produced lower cellular and humoral immune responses to M. pulmonis antigens than the resistant rat strain F344 after immunization.

Transfer of experimental autoimmune thyroiditis with T cell clones

We have investigated three T lymphocyte clones isolated from CBA/CaJ mice primed with mouse thyroid extract (MTE) in adjuvant. All three clones are L3T4+, Ig-, and Lyt2- and proliferate to MTE, mouse thyroglobulin (MTG) and rat thyroid extract. Clones A7 and B7 transfer thyroiditis to irradiated (475 rad) syngeneic mice, but not to normal recipients. The thyroid lesion induced by the B7 clone is characterized by the infiltration of both mononuclear and polymorphonuclear cells. The thyroiditis is transient in that lesions are apparent 7 and 14 days after transfer, but thyroids return to normal by day 21. Clone B7 showed helper activity for trinitrophenyl-keyhole limpet hemocyanin-primed B cells in vitro when stimulated with trinitrophenyl-MTG and also stimulated the production of anti-MTG antibody in recipient mice. Clone A7 induced thyroid lesions characterized by infiltration of the thyroid with mononuclear cells, with virtually no polymorphonuclear cell infiltration. This clone has shown no helper activity following stimulation with trinitrophenyl-MTG. The third clone (D2) proliferates to and shows helper activity to MTG, but fails to transfer thyroiditis to syngeneic, irradiated mice. On continuous culture, clone B7 lost its surface Thy. The loss of Thy appears unrelated to the ability to transfer thyroiditis since subclones of B7 with markedly different percentages of Thy+ cells transferred disease equally well.

HgCl2 induces nonspecific immunosuppression in Lewis rats

Brown-Norway (BN) rats injected with HgCl2 have been previously shown to develop a variety of autoimmune abnormalities. The susceptibility of BN rats is genetically controlled, and Lewis rats bearing a different RT1 haplotype are resistant. It will be shown in the present study that the number of MRC OX-8+ (suppressor/cytotoxic) cells increases in the spleen and lymph nodes of Lewis rats injected with HgCl2. The responsiveness to T cell mitogens and to alloantigens is concomitantly inhibited. Spleen cells from Lewis rats injected with HgCl2 fail to induce a local graft-vs.-host reaction. Data presented show that MRC OX-8+ cells are involved in the immunosuppression in Lewis rats treated with HgCl2. Furthermore, lymph node cells and MRC OX-8+ cells from these rats are able to inhibit the normal mixed lymphocyte reaction indicating that suppression is active. Thus, HgCl2 is able to trigger immune dysregulation leading either to autoimmunity or to immunosuppression depending upon the genetic background of the rat strain tested.

Therapy of rat autoimmune disease by a monoclonal antibody specific for T lymphoblasts

The central role of T lymphocytes in the initiation, regulation and propagation of autoimmune diseases defines them as most suitable targets for selective immunotherapy. The recent advance in culturing human and animal T cell lines allows us to select monoclonal antibodies specific for differentiation antigens expressed by activated T lymphocytes. We selected a monoclonal antibody cytotoxic for a subpopulation of activated rat T cells. In vivo, this antibody effectively blocks immune responses to foreign antigens or autoantigen and prevents development of autoimmune diseases like experimental allergic encephalomyelitis and adjuvant arthritis. Even already established disease can be blocked by a single injection of antibody. Furthermore, this monoclonal antibody can be used to monitor the course of autoimmune disease progression from peripheral blood samples.

Induction of experimental allergic neuritis in the BN rat: P2 protein-specific T cells overcome resistance to actively induced disease

T lymphocyte lines specific for the peripheral nerve myelin protein P2 were selected from the lymph nodes of Brown Norway (BN) rats immunized with bovine P2 protein in complete Freund's adjuvant. These T cells expressed the W3/25+, OX8-phenotype and responded specifically to bovine P2 protein, but not to PPD or bovine basic protein, in T cell proliferation assays. When injected i.v. into syngeneic recipients, BN P2-specific T cell lines induced both clinical and histologic signs of experimental allergic neuritis (EAN), overcoming the resistance of this rat strain to actively induced EAN. Although the histopathology of the disease was indistinguishable from that seen in T cell-mediated EAN in the Lewis rat, disease onset was considerably later, 7 to 8 days after cell transfer, as opposed to 4 days in Lewis. This lag phase between inoculation and disease onset could not be further reduced even by raising the cell dose to 50 X 10(6) cells/host. The fine specificity of the T cell response to P2 differs between Lewis- and BN-derived T cell lines. At least one neuritogenic epitope for each strain was present in the cyanogen bromide-derived peptide CB2 (residues 21-113), as shown by the ability of CB2-specific T cell lines derived from each strain to transfer EAN to the appropriate host strain. However, neuritogenic BN T lines fail to mount a response to the sequence 53-78 (SP4), which encompasses an epitope that is neuritogenic for Lewis rats. These results demonstrate that the resistance of BN rats to actively induced EAN is not due to the lack of appropriate P2-specific autoreactive T cell clones in the normal T repertoire. Furthermore, the results suggest that two distinct epitopes of P2 are responsible for EAN in Lewis and BN rats.

Regulatory effects of mast cells on lymphoid cells: the role of histamine type 1 receptors in the interaction between mast cells, helper T cells and natural suppressor cells

We have investigated the role of mast cells as modulators of lymphocyte function because the mast cells are concentrated in the areas of lymphoid storage; they are dependent upon T-cell growth factor for their proliferation; and they appear to be the principle if not sole storage site for histamine. We have tested the influence of mast cells on the proliferation of alloreactive cloned helper T cells, mixed leukocyte reactions, and the suppressive capacity of natural suppressor cells. We used an IL-3-dependent mast cell line that at high numbers (greater than 10(5)) suppressed and at low numbers (10(3) to 6 X 10(4)) augmented the proliferation of TH cells. Addition of histamine to cocultures enhanced the mast cell mediated proliferation of TH cells without directly affecting the helper cells. The action of histamine appeared to be mediated with H1 type receptors on these mast cells. Pretreatment of natural suppressor cells with supernatants from mast cell enhanced their suppressive capability. Here too, histamines enhanced suppression by the NS cell via histamine type 1 receptors on the natural suppressor cells. Our data suggest that mast cells may be a major modulator of the lymphoid cell immune function and demonstrate a role of histamine type 1 receptors in the interaction between mast cells, helper T cells, and natural suppressor cells.

Transplantation of the small bowel across MHC and non-MHC disparities in the rat

Using congenic strains of rats, the effect on the rejection of small bowel transplants across isolated major histocompatibility complex (MHC) and nonMHC antigenic disparities was examined. The medial survival time of small bowel grafts across MHC differences in the LEW anti-LEW.1N and LEW.1N anti-LEW strain combinations was 14 and 12 days, respectively. The median survival time across the nonMHC antigenic difference in the BN anti-DA.1N strain combination was 20 days, which was significantly longer than the rejection time across the MHC differences (P less than 0.005). Both hemagglutinating and cytotoxic antibodies were produced in all three strain combinations, but the magnitude of the response varied considerably and did not correlate with the time of rejection. In the case of MHC differences, the antibody was directed against both class I and class II antigens, and with the nonMHC difference, the greatest response was directed against the major blood group antigen RT2.

Induction of B cell tolerance in rats by large doses of allogeneic erythrocytes

Several studies have now confirmed our original observation that transfusions of large doses of donor-specific allogeneic erythrocytes (E) induce humoral unresponsiveness to E-associated antigens (including major histocompatibility complex (MHC) class I antigens) in rats, which is associated with prolonged survival of subsequently inserted renal grafts. To examine whether this tolerance was due to induction of suppressor (T) cells or to anergy or deletion of antigen-specific B cells, an in vitro system was developed that allowed generation of primary immune responses of rat splenocytes to allogeneic erythrocytes. Cocultivation of B and non-B cells from tolerant and normal rats in this system showed that E transfusions had induced B cell tolerance in the recipients; no evidence was obtained that suppressor T cells were involved in the maintenance of unresponsiveness. On the contrary, non-B cells from tolerant rats could "help" normal B cells for antibody formation to allogeneic E. In vivo, tolerance to allogeneic E could be broken in one rat strain combination by skin allografts. Therefore, the state of B cell tolerance induced by E transfusions may be referred to as "reversible clonal anergy".

Abrogation of the immunosuppressive effect of donor spleen cells on renal allografts in the rat by irradiation or heat treatment

In the donor-recipient strain combination Lewis (RT1l) to Dark Agouti (RT1a), indefinite renal allograft survival (MST greater than 100 days) was induced by pretreating recipient animals i.v. with 10(6) to 10(8) viable spleen lymphocytes, seven days before transplantation. Pretreatment with 10(4) or 10(5) cells was ineffective (MST 10 days). However when 10(7) live, but heat-treated (55 degrees C for 10 min) or irradiated (1000 rads) cells were used, all the animals rejected the allograft in a normal fashion (MST 10 and 11 days, respectively). Median survival time of third-party controls was 10 days. The relative amount of cell surface major histocompatibility antigens (class I and class II) expressed by the three spleen cell preparations was investigated using monoclonal antibodies and fluorescence activated cell sorter analysis and found to be similar. After 24 hr in culture, only 1% of heat-treated and 10% of irradiated cells were viable, in contrast to 75% of untreated splenocytes. Trafficking of these lymphocytes in recipient animals was investigated by 51chromium labeling of the cells: 30% of lymphocytes had localized in the liver within 3 hr with little difference in localization among the different cell preparations. But, although 20% of normal and irradiated cells localized in the spleen within 3 hr, at no stage were more than 5% of the heat-treated cells found in the spleen. It is suggested that the length of time viable donor lymphocytes remain in the recipient circulation is important in the induction of specific immunosuppression by spleen lymphocytes.

Immune sensitization to syngeneic organ-specific intestinal antigens in the Lewis rat

In human chronic inflammatory bowel disease involving mucosal epithelium, sera and lamina propria mononuclear cells are reactive with cell surface components isolated from gut epithelial cells. To define a model system in which the disease-inducing potential of such immune factors could be rigorously evaluated, we sought to immunologically sensitize inbred murine strains to syngeneic colonic epithelial cell-associated components (ECAC-C), to define precise in vivo and in vitro conditions to optimize ECAC-C reactivity, and to initially explore whether such cells could elicit tissue injury in epithelium after adoptive transfer to naive animals. Following footpad immunization, Day 42 lymph node cells but not splenocytes were reactive with syngeneic ECAC-C, as shown by a linear increase in [3H]thymidine incorporation over a wide range of antigen concentration (0.5 to 100 micrograms/ml). A subsequent 48-hr exposure to ECAC-C and/or interleukin 2 resulted in a more restricted responsiveness, proliferation occurring only in the presence of ECAC-C or mitogen and not to a coimmunogen (PPD). Further evidence that lymph node cells from ECAC-C/CFA immunized animals were indeed sensitized to syngeneic ECAC-C included ability of donor animals to mount highly significant earlobe DTH responses to ECAC-C, indicating the presence of antigen-specific T-DTH cells, and the failure of polymyxin B, in doses sufficient to inhibit LPS-induced mitogenesis, to reduce lymph node cell responsiveness to ECAC-C, known to be contaminated with LPS. ECAC-C-specific circulating antibody and T-cytotoxic cells were not detected. Adoptive transfer of Day 42 lymph node cells, sensitized in vivo and conditioned in vitro, was not associated with tissue injury in syngeneic recipients in preliminary experiments. This model system, with antigen-specific cells analogous to those present in diseased mucosa of human chronic inflammatory bowel disease, may be an important means to determine the pathophysiologic significance of anti-epithelial cell immune responses in these disorders.

Polyclonal activation of rat splenic lymphocytes after in vivo administration of Mycoplasma pulmonis and its relation to in vitro response

The plaque-forming cell (PFC) assay with sheep erythrocytes (SRBC) sensitized with different antigens and a 4-h tritiated thymidine pulse assay were used to determine whether polyclonal activation occurs in rats following in vivo administration of Mycoplasma pulmonis. Injection of M. pulmonis into F344 rats resulted in an increase in the number of splenic immunoglobulin M-secreting PFC that produced antibodies reactive with the trinitrophenyl hapten and with SRBC. This polyclonal response reached a peak by 72 h after injection and returned to normal levels by 96 h, at which time the specific response to M. pulmonis reached its peak. Heat treatment and preopsonization of M. pulmonis with antiserum before injection resulted in reduced numbers of PFC against M. pulmonis-sensitized SRBC, trinitrophenyl hapten-sensitized SRBC, and SRBC. The number of PFC against the three types of target cells also increased in LEW rats after immunization with M. pulmonis. The number of PFC against SRBC and staphylococcal protein A-sensitized SRBC was higher in immunized LEW rats than in immunized F344 rats. Examination of unimmunized animals also revealed that LEW rats had higher initial numbers of PFC than did F344 rats. These results showed that polyclonal activation occurs in rats following in vivo administration of M. pulmonis and that LEW rats have an inherent propensity to develop higher nonspecific responses in vivo than F344 rats.

Oxygen-independent killing by alveolar macrophages

We have found that normal alveolar macrophages can kill an intracellular parasite by a mechanism that does not involve toxic metabolites of oxygen. We studied the interaction between Toxoplasma gondii and rat alveolar macrophages in vitro. We were interested in Toxoplasma because it causes pneumonia in immunosuppressed patients but not in healthy individuals, and we chose the rat because it resembles immunocompetent human subjects in being resistant to T. gondii. Resident rat alveolar macrophages could kill large numbers of T. gondii. This occurred without a respiratory burst as judged by intracellular reduction of nitroblue tetrazolium and quantitative release of superoxide. Furthermore, scavengers of toxic oxygen metabolites had no effect on the toxoplasmacidal activity of the alveolar macrophages, nor did prior exhaustion of their respiratory burst with PMA. Whereas acid pH (e.g., 4.5-6.0) rapidly kills extracellular T. gondii, raising of the intralysosomal acid pH of rat alveolar macrophages by incubating them with weak bases did not inhibit their ability to kill T. gondii. Killing of Toxoplasma occurred within 1 h of initial exposure to the alveolar macrophages. However, there was no evidence that killing preceded ingestion; Toxoplasma attached to the surface of the cell appeared viable, and when phagocytosis was blocked with sodium fluoride the organisms survived. These results indicate that rat alveolar macrophages possess a powerful nonoxidative microbicidal mechanism, which is distinct from acidification of the phagolysosome but which probably involves phagosome formation. This mechanism may be clinically relevant, for we have recently observed that human alveolar macrophages also kill T. gondii by an oxygen-independent process.

Immunogenicity and crossreactivity of specificity-associated markers on alloreactive T cells. Confirmation based on the model of tolerance abolition by adoptive transfer

Syngeneic or parental strain T cells adoptively transferred into hybrid rats tolerant of third party alloantigens (L/DA tolerant of BN), in numbers insufficient to abolish tolerance, induce instead an active resistance to tolerance abolition with larger, usually effective dosages of donor cells. Of particular interest is the finding that immunization with T cells from one parental strain donor (e.g., DA) inhibited the tolerance-abolishing alloreactivity (anti-BN) of subsequently transferred T cells from the same (DA) and the other (L) parental strain donor. We conclude that anti-MHC receptors on T cells from different genetic backgrounds reactive to the same third party alloantigens share the same conserved immunogenic specificity-associated markers (SAM). The nonpolymorphism of anti-MHC receptors shown here in the transplantation tolerance model is a confirmation of the same conclusion drawn from earlier studies with the GVHD-resistance model, and it therefore suggests that these two models of T cell MHC interactions involve very similar mechanisms of T cell idiotypic regulation.

Composite tissue (limb) allografts in rats. III. Development of donor-host lymphoid chimeras in long-term survivors

Eight LEW rat recipients possessing long-term-surviving (206-701 days) LBN vascularized hind limb allografts (CTAs) were tested for donor-host lymphoid chimerism. The recipients received various cyclosporine (CsA) treatment protocols in order to induce indefinite CTA acceptance. Histological examination of long-term-surviving CTAs demonstrated normal-appearing bone marrow in the donor limb. Lymphocytes isolated from host hemopoietic tissues (peripheral blood and/or spleen) by ficoll-hypaque density gradient centrifugation were tested against LEW-anti-BN antisera. Comparisons were made to standard curves employing various known concentrations of LBN and LEW cell combinations. The level of lymphocyte agglutination (dependent variable) showed a significant (P less than 0.025-0.005) linear relationship to the concentration of LBN donor cells (independent variable) present. Lymphocyte suspensions isolated from long-term CTA host peripheral blood and/or spleen showed a mean of 19.7% (+/- 9.7-95% confidence interval) donor LBN mononuclear cells present. Thus, it appeared that lymphoid cells originated from, and/or were released from LBN donor bone marrow into the circulation, resulting in chimeric repopulation of hemopoietic tissues. The presence of donor immunocytes in these limb allograft recipients may have been beneficial, and thus could have helped contribute to the long-term CTA survival observed.

Requirement for both MHC and non-MHC antigens residing on the same erythrocyte for donor erythrocyte-mediated prolongation of rat renal allograft survival

Transfusions of highly purified LEW erythrocytes (E) administered to BN recipients prior to insertion of LEW kidneys markedly prolonged the survival of these allografts (greater than 35 days). Administration of E from syngeneic (BN), third-party (PVG), and MHC-congenic LEW.1N or BN.1L rats did not improve LEW kidney graft survival to the same extent (less than 14 days). BN.1L E were shown to carry at least the same quantity of LEW MHC antigens on their surface as LEW E, thus the failure to prolong LEW kidney graft survival is due to the absence of LEW non-MHC antigens from BN.1L E. Attempts to substitute for this deficiency by mixing LEW.1N E to BN.1L E prior to transfusion failed to restore the beneficial effect, demonstrating that donor E-mediated prolonged renal allograft survival requires the presence of both MHC and non-MHC alloantigens on the same E.

Experimental allergic encephalomyelitis: clinical disease and enhanced cellular transfer in the absence of lymphocyte proliferative responses against syngeneic MBP

Experimental allergic encephalomyelitis (EAE) was induced in Lewis rats using several different immunization protocols, and draining lymph node cells from these animals were assayed for proliferation against heterologous, homologous, and syngeneic MBP, and syngeneic spinal cord. Proliferative responses were largely stimulated by nonsyngeneic antigenic determinants and correlated better with the antigen used to induce EAE than with signs of autoimmune disease. Lymph node cells from rats immunized with either guinea pig spinal cord or syngeneic MBP did not proliferate measurably when restimulated in vitro with syngeneic MBP, yet lymphoid cells from these animals were enhanced in their capacity to transfer EAE following in vitro stimulation with syngeneic MBP.