Identification, isolation, and characterization of a novel cytotoxin in murine cytolytic lymphocytes

Murine cytotoxic T lymphocytes contain, in addition to the cytotoxic pore-forming protein perforin, another cytolytic factor localized in both cytoplasm and granules. Like perforin, this CTL cytotoxin lyses a variety of tumor cells; unlike perforin, it is stable in the presence of calcium, requires several hours to induce maximal lytic activity, and is antigenically related to the previously described tumor necrosis factor (TNF) and lymphotoxin (LT). However, it differs from TNF and LT in a number of biochemical and functional properties. TNF- and LT-specific cDNA probes did not hybridize with any CTL-specific message, indicating that the CTL cytotoxin is distinct from those two factors. It has an apparent Mr of 50 and 70 kd under reducing and nonreducing conditions, respectively, is secreted by secretagogue-stimulated CTLs, and causes DNA fragmentation in several targets, a phenomenon previously attributed to target cell damage by CTLs. These results suggest that killing by lymphocytes may encompass multiple mechanisms and polypeptides.

[Determination of sub-populations of circulating T lymphocytes in alcoholic cirrhosis using monoclonal antibodies OKT3, 4, 5, Leu 2 and Leu 15. Effect of hepatitis B virus infection]

Peripheral T lymphocyte subpopulations were quantified in 24 alcoholic cirrhotic patients, 11 of them having anti-HBs and/or anti-HBc antibodies, and were compared with 35 healthy control subjects, 10 of them having anti-HBs and/or anti-HBc antibodies. The monoclonal antibodies utilized (OKT3, OKT4, OKT8 in simple staining, Leu 2 and Leu 15 in double staining) are considered as markers of mature (CD3), helper (CD4), cytotoxic/suppressor (CD8, Leu 2), suppressor (Leu [2+ 15+), and cytotoxic (Leu 2+ 15-) T cells. In cirrhotics, when compared to controls, the number of CD3 cells was reduced (p less than 0.01); the proportion of CD4 cells was within normal range, and that of CD8 cells diminished (p less than 0.001), contrasting with an increased proportion of Leu 2+ cells (p less than 0.01), related to an increased proportion of Leu 2+ 15+ cells. Leu 2+ 15- lymphocytes were within normal range. In control subjects, a decreased proportion of Leu 2+ 15+ cells was found (p less than 0.05) when Ac HBs and/or Ac HBc were present. In cirrhotics having at least one serologic marker of hepatitis B virus infection, when compared with negative ones, increased proportions of Leu 2+ (p less than 0.05) and Leu 2+ 15+ (p less than 0.05) cells were found. These results show that data concerning T lymphocyte subpopulations are conflicting when various types of antibodies are used. However, they suggest abnormalities of immune regulation, possibly a defect of T suppressor cell function. Hepatitis B virus infection probably modifies immune regulation in alcoholic cirrhosis, and perhaps in normal subjects.

Characterization of a product of histoincompatible spleen cells restoring class I-inhibited mixed-lymphocyte culture reactions

Conditions leading to the formation of a recognition product (SEPIR) capable of restoring MLC responses inhibited by treating stimulator cells with mAb to Class I antigens have been investigated. SEPIR has been found to be present in supernatants of immunological one-way interactions of histoincompatible spleen lymphocytes from naive mice following cultivation for a few hours. It is active in relatively high dilutions. Similarities with cytokines of IL-1, IL-2, or interferon character could not be revealed. Formation of the heat-labile principle is governed by immunologically specific reactions and involves recognition of Class I (but not Class II) HMC antigens by T cells of Lyt-2 phenotype. B cells and Lyt-1+ cells failed to induce formation of the product. SEPIR appears to be a complex of T-cell receptors for Class I antigens with these antigens. The data indicate that in conventionally induced fully incompatible MLC responses a similar product might be formed.

Transcription of a T cell receptor beta chain gene in L cell fibroblasts following DNA-mediated gene transfer

Functionally rearranged T cell receptor alpha and beta-chain genes from a fluorescein-specific cytotoxic T cell clone have been introduced, together with the selectable marker gene neo, into mouse fibroblasts (L cells) by electroporation. Transformed cells were selected for neo gene expression by growth in medium containing the antibiotic G418. Southern blot analysis of DNA from transformed L cell clones revealed that the endogeneous T cell receptor alpha and beta-chain genes were in germ-line configuration and that in 4 of the 6 clones examined the exogenously introduced rearranged alpha and beta chain genes were present. The introduced beta-chain gene is transcriptionally active in two L cell clones examined whereas no transcription of the alpha-chain gene could be detected in the same transformants.

Graft rejection in recipients of T-cell-depleted HLA-nonidentical marrow transplants for leukemia. Identification of host-derived antidonor allocytotoxic T lymphocytes

Clinical trials with bone marrow depleted of donor T lymphocytes indicate that both the incidence and severity of graft-versus-host disease (GVHD) in patients undergoing bone marrow transplantation (BMT) for treatment of leukemia are greatly reduced. However, there has been a concurrent increase in the incidence of graft rejection, particularly among recipients of HLA-nonidentical marrow grafts. In order to investigate the nature of graft failure, peripheral blood mononuclear cells (PBMC) present at the time of graft failure have been characterized by phenotypic and functional analyses in 5 recipients of HLA-nonidentical marrow grafts. Rejection of HLA-nonidentical marrow grafts was associated with the emergence of host-derived T lymphocytes in all 5 patients. In 3 of these patients, the cells could be tested directly for cell-mediated cytotoxicity. Antidonor cytotoxicity was detected in each of these 3 patients. In one patient the target specificity of the cytotoxic lymphocytes was identified as the donor class I HLA antigen, HLA-B7. None of the patient PBMC mediated cytotoxicity against the natural killer cell target K562.

Distinction of virgin and memory T lymphocytes. Stable acquisition of the Pgp-1 glycoprotein concomitant with antigenic stimulation

The Pgp-1 glycoprotein was identified on a minor (27%) subset of peripheral Lyt-2+ or L3T4+ T cells. In contrast, mature medullary-type thymocytes (Lyt-2+ L3T4-, Lyt-2- L3T4+) were nearly devoid of cells expressing detectable surface Pgp-1. The appearance of peripheral Pgp-1- T cells was found to be thymus dependent, as demonstrated by the diminished proportion of Pgp-1- T cells after thymectomy and their virtual absence in athymic nude mice. The subsequent acquisition of surface Pgp-1 was found to be a stable differentiation event occurring concomitantly with primary antigenic stimulation; selected Pgp-1- mature T cells from thymus or periphery acquired constitutive expression of Pgp-1 after stimulation in vitro with alloantigen or mitogens. These observations were extended by studies in vivo showing that immunization with various antigens augmented the percentage of Pgp-1+ spleen cells within the Lyt-2+ subset. Furthermore, the frequencies of antigen-specific CTLp, after immunization by any of three different antigens tested, were greatly enriched in the Pgp-1+ compared with the Pgp-1- subpopulations. Peritoneal exudate Lyt-2+ cells, after a localized allograft rejection, demonstrated a particularly prominent Pgp-1+ subpopulation (78%) that contained virtually all the allospecific cytolytic activity. A model consistent with all of these data proposes that mature thymocytes lacking surface Pgp-1 upon emigration to the periphery acquire its expression at the time of primary antigenic stimulation. Hence, expression of Pgp-1 among peripheral T cells is an important differentiation marker for identifying antigen-stimulated memory T cells.

Duodenal mucosal T cell subpopulation and bacterial cultures in acquired immune deficiency syndrome

Enteric infections, chronic diarrhea frequently with no obvious etiology, and weight loss cause major morbidity and mortality in acquired immune deficiency syndrome (AIDS). Alterations in mucosal immunity may explain the increased incidence of enteric infections, and contamination of the upper small intestine with bacteria may be the cause of weight loss observed in these patients. To test this hypothesis we studied the mucosal T lymphocyte subset in duodenal mucosal biopsies in 14 AIDS and seven control patients. Duodenal fluid was also cultured for aerobic and anaerobic bacteria. There was a significant decrease among leu-3a T cells (helper/inducer) subset in AIDS. The proportion of mucosal T cells reacting with leu-2a (cytotoxic/suppressor) was significantly increased in AIDS patients. These patients also had a significant reversal of the normal mucosal helper/suppressor T cell ratio. There was no change in the number of leu-7 cells (cells mediate natural killer and antibody-dependent cellular cytotoxicity) as compared to controls. All patients with diarrhea and three of five patients without diarrhea had bacteria in their duodenal fluid. Mean number of organisms was 4.5 X 10(4)/ml. Cultures were negative in all control subjects. The results reveal that the abnormalities of T cell subpopulation in the blood of AIDS patients also occur in their duodenal mucosa. This immunological abnormality is associated with the bacterial colonization of upper gastrointestinal tract which may explain the diarrhea and weight loss observed in majority of our patients. The results also indicate that increased incidence of enteric infections in AIDS may be explained on the basis of altered mucosal immunity.

Structure of a cytotoxic T-lymphocyte-specific gene shows a strong homology to fibrinogen beta and gamma chains

Using a subtractive cDNA cloning method, we isolated a number of T-lymphocyte-specific genes. One of these genes, represented by the cDNA clone pT49, is expressed in cytotoxic T lymphocytes but not in helper T lymphocytes or B lymphocytes. The protein structure deduced from the nucleotide sequence showed a high degree of homology to fibrinogen beta and gamma subunits. This might indicate that evolutionarily fibrinogen has its origin in lymphocytes. In spite of the strong homology of pT49 protein to the fibrinogen subunits, the positions of the introns in the pT49 gene are totally different from those of the fibrinogen genes.

Characterization of the high-affinity cell-surface receptor for murine B-cell-stimulating factor 1

Radiolabeled recombinant murine B-cell-stimulatory factor 1 (BSF-1) was used to characterize receptors specific for this lymphokine on the surface of primary B and T cells and in vitro cell lines representing the B-cell, T-cell, mast cell, macrophage, and myelomonocytic lineages. BSF-1 binding was rapid and saturable at 4 degrees C and 37 degrees C with a slow dissociation rate. On all cell types examined, BSF-1 bound to a single class of high-affinity receptor (less than 2000 receptors per cell) with a Ka of 10(10)-10(11) M-1. Receptor expression on resting primary B and T cells was low (less than 100 receptors per cell), whereas activation with lipopolysaccharide or Con A produced a 5- to 10-fold increase in receptor numbers. Among a panel of lymphokines and growth hormones, only unlabeled BSF-1 was able to compete for the binding of 125I-labeled BSF-1. Affinity crosslinking experiments resulted in the identification on all cells tested of a receptor protein with an average Mr of 75,000.

Differential expression of asialo GM1 on alloreactive cytotoxic T lymphocytes and lymphokine-activated killer cells

The present study was undertaken to examine the differential expression of asialo GM1 (AsGM1) on the responding cells and effectors of alloreactive cytotoxic T lymphocytes (CTL) and lymphokine-induced activated killers (LAK). It was found that AsGM1 was expressed on the 3-day-cultured LAK effectors. Its expression gradually disappeared to the extent that AsGM1 became undetectable after 5 to 6 days of culturing. In contrast, AsGM1 was detected on 3-day CTL generated in mixed-lymphocyte cultures (bulk cultures); however, the levels of AsGM1 expression remained the same for at least 7 days. When examining the expression of AsGM1 on the responding cells, the reciprocal results were obtained. AsGM1 was expressed the LAK responders, but we were unable to demonstrate AsGM1 on CTL responders. Depletion of AsGM1+ cells from the responding population reduced subsequent CTL responses; however, CTL responses could be restored by adding conditioned media containing both interleukin 2 (IL-2) and other helper-T-cell factors and could not be restored by purified IL-2 alone adding at comparable doses. Reconstituting the AsGM1-depleted responders with Lyt-2-depleted splenocytes also restored the CTL response. Furthermore, depletion of AsGM1 cells from the responding population did not reduce the precursor frequency of allo-CTL, whereas the precursor frequency of LAK cells was reduced 42-fold. These findings show that the reduction of CTL responses after depletion of AsGM1+ cells was not due to the removal of precursors; instead, the defect appeared to be in the helper population. We further found that the helper defect was not due to impaired IL-2 production, because the endogenous production of IL-2 AsGM1-depleted responders was not reduced. Therefore, AsGM1+ cells may play a role in the helper pathway other than IL-2 production.

Immunological abnormalities in asymptomatic homosexual men: correlation with antibody to HTLV-III and sequential changes over two years

A prospective study on 100 homosexual male volunteers was designed to examine immunological function in relation to sexual activity and infection with the human T cell lymphotropic virus Type III (HTLV-III). Complete data were available for 71 men. In a comparison with 100 age-matched heterosexual men, the study group of 100 men had a significantly higher mean serum IgG level (12.1 +/- SD 2.7 g/l vs. 10.9 +/- 2.4 g/l, p less than 0.01) and a significantly lower mean number of CD4 (T4) cells (845 +/- 310 X 10(-6)/l vs. 1128 +/- 375; p less than 0.01). For the study group, seropositivity for anti-HTLV-III was present initially in 22 per cent and was associated with a higher mean level of serum IgG and lower mean number of CD4 cells. Among seropositive homosexual men a low CD4/8 ratio was attributable to low numbers of CD4 cells in those without lymphadenopathy and to high numbers of CD8 cells in those with lymphadenopathy. For the seronegative homosexual men, a low CD4/8 ratio as a result of an increased CD8 cell count was present in 12 of 60, and was associated with numerous sexual partners and semen culture positive for cytomegalovirus. In two seropositive subjects a low CD4/8 ratio due to a decrease in the CD4 cell count was predictive of the development of AIDS by some two years. For the 71 men with complete data over two years, indices of cell-mediated immunity, including mean counts of CD4 cells, the CD4/8 ratio, and score for recall of cutaneous delayed type hypersensitivity increased during the first year but not during the second year in both seropositive and seronegative subjects. These increases occurred in association with changes in sexual practices and activity, but could not be attributed to any one particular factor.

A phosphorylated, disulfide-linked membrane protein in murine cytotoxic T lymphocytes

The previously determined sequence of the murine T-cell gamma gene and its transcription in cloned T lymphocytes suggests that the polypeptide encoded by this gene is generally present in cytotoxic T cells as a 33-kDa monomer in a disulfide-bonded dimer. The gamma chain is also expected to be phosphorylated because a sequence in its cytoplasmic domain is homologous to an active site for serine phosphorylation in the regulatory subunit of cAMP-dependent protein kinase. We describe here a cytotoxic-T-cell-associated phosphorylated protein, many of whose properties suggest that it may be the product of the T-cell gamma gene. Its phosphorylation is greatly enhanced by interleukin 2 stimulation.

Exogenous IL2 partially reverts CML non-reactivity acquired during prophylactic immunosuppression with cyclosporin A of human allograft recipients

Proliferative and cytolytic lymphocyte responses and the influence of exogenous interleukin 2 (IL2) on cell-mediated lympholysis (CML) reactivity were evaluated in 12 allograft recipients. Responses were induced by mitogenic lectins or by donor and third-party cells. Patients were tested immediately before transplantation (Tx) and one and three months after grafting. Prophylactic immunosuppression consisted of Cyclosporin A (CyA) and low-dose prednisone (P). Analysis of post transplant cells revealed a reduced overall proliferative T cell responsiveness induced by both alloantigens and mitogenic lectins. No evidence for donor-specific reduction of MLC responses was seen. Overall CML reactivity of post-Tx lymphocytes was also impaired. This was accompanied by donor-specific CML non-reactivity in six of seven patients with quiescent grafts. In these patients, the cytolytic potential against donor cells could be restored when maximal T cell help via exogenous IL2 was provided.

Generation of cytotoxic T lymphocyte responses to allo-H-2 antigens in allogeneic bone marrow chimeras histocompatible at the H-2 subregions

The present study was performed to determine whether H-2 matching is required for full cytotoxic T lymphocyte (CTL) responses to allo-H-2 antigens in allogeneic bone marrow chimeric mice. A number of irradiated, bone marrow-reconstituted chimeras constructed from various combinations of marrow cells from B10 H-2 recombinant strains and AKR recipient mice were prepared. Spleen cells obtained from such chimeras and normal control mice were activated in vitro by culturing them with irradiated stimulator cells. It was shown that spleen cells from [4R----AKR], [(4R X 3R)F1----AKR] or [AQR----AKR] chimeras, which were histocompatible on the left hand-side of the H-21 subregion between donor and recipient mice, generated greater CTL activities than those that were seen with spleen cells of [3R----AKR] or [5R----AKR] chimeras, which were histoincompatible in this region. We were unable to demonstrate suppressor cell activity of the spleen cells of [3R----AKR] chimeras cultured with stimulator cells. Although spleen cells from [3R----AKR] chimeras showed substantial proliferative responses to stimulator cells (MLR) and to Con A and LPS, IL2 activities of supernatants from Con A-activated spleen cells (Con A SN) of the chimeras were significantly lower than those of [4R----AKR] or [(4R X 3R)F1----AKR] chimeras. Furthermore, vigorous CTL activities were obtained with either spleen cells or thymocytes from [3R----AKR] chimeras when rat Con A SN was added to the MLR cultures. These observations suggest that the numbers of precursor CTLs in the cells from [3R----AKR] chimeras are at the same level as those of [(4R X 3R)F1----AKR] or normal mice and that the low CTL activities generated by spleen cells of [3R----AKR] chimeras compared to H-2I-matched chimeras are due in large measure to deficiency in IL2 production by the splenic T cells of the [3R----AKR] chimeras.

Glutathione augments the activation of cytotoxic T lymphocytes in vivo

The activation of cytotoxic T lymphocytes (CTL) in vivo was found to be augmented by glutathione if injected i.p. in the late phase but not in the early phase of the response. The effect of glutathione possibly resembles the augmenting effect of 2-mercaptoethanol in lymphocyte cultures.

Properties of a purified pore-forming protein (perforin 1) isolated from H-2-restricted cytotoxic T cell granules

Histocompatibility-restricted cytotoxic T lymphocytes produce circular lesions on target cell membranes. The pore-forming protein (PFP or perforin 1) that forms these membrane lesions has been purified from lymphocytes. At 37 degrees C, in the presence of Ca2+, this protein polymerizes into a supramolecular tubular complex of Mr greater than 10(6) that partially resists dissociation by SDS and reducing agents. It incorporates spontaneously into planar lipid bilayers during polymerization to form nonselective ion channels, showing heterogeneous size distribution, the smallest conductance per unit being identified as 400 pS in 0.1 M NaCl. PFP/P1 that had been assembled in lipid vesicles before incorporation into planar bilayer show much larger single channel conductance, ranging from 1 to 6 nS in 0.1 M NaCl, suggesting that PFP/P1 may assume multiple functional sizes in proportion to its state of polymerization. The reconstituted channels are relatively voltage-insensitive, with most channels persisting in the open state for seconds to minutes. Nucleated cells are rapidly depolarized by this protein. The purified protein lyses a variety of tumor cells. Polymerization and functional channel activity are absolutely Ca2+-dependent. The activity of this protein may play a direct role in T lymphocyte-mediated cytolysis.

No functional gamma-chain transcripts detected in an alloreactive cytotoxic T-cell clone

Three groups of genes that undergo rearrangements during T-cell maturation have been isolated from T cells. Two of them encode the alpha- and beta-subunits of the T-cell antigen receptor and are shared between antigen-specific, major histocompatibility (MHC) class I-restricted cytotoxic T cells and antigen-specific, MHC class II-restricted helper T cells. The third group of genes, called gamma, is preferentially transcribed in cytotoxic T cells. This led to the hypothesis that the unidentified gamma-gene products could be part of a putative T-cell receptor responsible for MHC class I recognition. We report here on the isolation of three different types of gamma-gene transcripts of an alloreactive cytotoxic T-cell clone (3F9). Two are derived from two rearrangements that have occurred at the same locus (V gamma 10.8A to J gamma 10.5 and transcribed with C gamma 10.5), while the third involves a new V gamma-gene segment that is joined to J gamma 13.4 and transcribed with C gamma 13.4. All these rearrangements are abortive and lead to the formation of non-functional gamma-chain genes because the proper translational reading frame is not maintained. Because the second copy of the C gamma 13.4 gene segment is deleted and as C gamma 7.5 is considered to be a pseudogene and has not undergone any rearrangements in 3F9, we conclude that the alloreactive cytotoxic T-cell clone 3F9 does not contain a functional transcript of a known gamma-chain gene.

A functional gamma gene formed from known gamma-gene segments is not necessary for antigen-specific responses of murine cytotoxic T lymphocytes

Structural similarities between surface immunoglobulins (s Ig) on B cells and antigen-specific receptors on T cells suggest that a T cell, like a B cell, should express only two immunoglobulin-like genes, one for each subunit of the disulphide-linked, heterodimeric, antigen-specific (alpha beta) T-cell receptor. However, cytotoxic T lymphocytes (Tc cells) and immature thymocytes also contain RNA transcripts of a third immunoglobulin-like gene, called gamma (refs 1-4). A polypeptide corresponding to the gamma gene has not yet been identified and the function of this gene remains an enigma. Judging from its nucleotide sequence, the rearranged gamma gene is expected to encode an integral membrane polypeptide chain, and gamma complementary DNAs from two cloned Tc cell lines have previously been found to have different sequences around the V-J (variable region-joining region) junction, suggesting that, in these cells, the gamma-gene product is a clonally diverse surface structure that may form part of an as yet unidentified, antigen-specific receptor. To analyse further the extent of diversity of the gamma-gene product, we have determined the partial sequences of 11 gamma cDNA clones from three other cloned Tc cell lines, and report here that the sequences are indeed clonally diverse, but in all instances they are out-of-phase in the region of the V-J junction. This finding and the pattern of gamma-gene rearrangements in these cell lines indicate that a polypeptide product of the previously reported gamma gene, V2J2-C2, is not expressed in them and is, therefore, not necessary for the antigen-specific cytotoxic and proliferative responses of these mature T cells.

A semiautomated hemolysis microassay for membrane lytic proteins

A simple, rapid, semiautomated microassay for hemolysis using a microtiter plate spectrophotometric system is described. The assay relies on the differences in light scattering (turbidity) properties of intact and of lysed erythrocytes. Lysis of erythrocyte suspensions in 96-well plates is determined by absorbance at 690 nm. A linear correlation between the percentage of hemolysis and the turbidity decrease is observed, indicating that this assay may be used for both rapid screening and quantitation of the hemolytic activity. This assay allows screening of 300 samples in less than 6 min. Small samples derived from protein fractionation columns (HPLC, for example) can be rapidly screened. This assay has been used in the successful isolation of a cytolytic membrane-lytic protein from the granules of cloned cytotoxic T lymphocytes and NK cells.

Immune alterations in hemodialyzed patients. I. Effect of blood transfusion on T-lymphocyte subpopulations in hemodialyzed patients

The immune status in 42 patients with end-stage renal failure on maintenance hemodialysis was studied by using monoclonal antibodies to lymphocyte subpopulations. Lymphopenia, reductions in the proportion of OKT4+ cells and OKT4+/OKT8+ cell ratio were observed in hemodialyzed patients. These alterations in immune status were observed in 34 transfused patients, but not in 8 patients without history of blood transfusion. The proportion of OKT8+ cells was increased in patients with history of blood transfusion. When transfused patients were divided according to the dose of blood transfused in the last 2 yr, the most serious change was observed in those who received greater than 10 u of transfusion. The dose of blood transfused in the last 2 yr correlated positively with the proportion of OKT8+ cells (p less than 0.01) and inversely with OKT4+/OKT8+ cell ratio (p less than 0.05). The duration of hemodialysis did not affect the alterations in immunoregulatory cells. These results indicate that alterations in immune features in hemodialyzed patients may be linked to the history of blood transfusion rather than that of uremia and/or hemodialysis.

Nonspecific influx of cytotoxic T cells into influenza virus-infected lungs of mice

The influx of cytotoxic T cells into A/WSN influenza virus-infected mouse lungs was investigated by adoptive transfer with [125I] 5-iodo-2'-deoxyuridine ([125I]UdR)-labeled syngeneic cells. More A/WSN virus-immune secondary effector T cells were localized in the A/WSN virus-infected lungs than in the uninfected lungs, the ratios being in the range 2.5-5.0 Nonimmune control cells, in contrast, showed no significant difference in the localization pattern in infected compared to uninfected lungs. Virus-immune T cells of different antigenic specificities, i.e., Sendai or Semliki Forest virus-immune secondary effector T cells, however, also localized more in A/WSN virus-infected than in uninfected lungs, but the heterologous virus-immune T cells were retained in the A/WSN virus-infected lungs for a shorter time than A/WSN virus-immune secondary effector T cells. The work suggests mechanisms other than antigenic specificity may be important in the localization of immune T cells in virus-infected lungs.

Modulation of cellular immunity in medical students

This study assessed the psychosocial modulation of cellular immunity in 34 medical-student volunteers. The first blood sample was obtained 1 month before examinations, and the second on the day of examinations. There were significant declines in the percentage of helper/inducer T-lymphocytes, in the helper/inducer-suppressor/cytotoxic-cell ratio, and in natural killer-cell activity in the blood samples obtained on the day of examinations. Half of the subjects were randomly assigned to a relaxation group which met between sample points; the frequency of relaxation practice was a significant predictor of the percentages of helper/inducer cells in the examination sample. Three biochemical nutritional assays (albumin, transferrin, and total iron-binding protein) were within normal limits on both samples. Data from the Brief Symptom Inventory showed significantly increased global self-rated distress associated with examinations in the no-intervention group, compared to nonsignificant change in the relaxation group. Clinical and theoretical implications are discussed.

Temporal changes of suppressor T lymphocytes and cytotoxic T lymphocytes in syngeneic murine malignant gliomas

The temporal activities of suppressor T lymphocytes (Ts) and cytotoxic T lymphocytes (CTL) were investigated in a syngeneic murine malignant glioma (a methylcholanthrene-induced ependymoblastoma of C57BL/6 mouse origin, 203-glioma). After the s.c. tumor inoculation, it was suggested that both Ts and CTL were generated with target specificity against 203-glioma cells, because neither Ts nor CTL activity were seen against syngeneic EL 4 (benzpyrene-induced thymoma), allogeneic P815 (methylcholanthrene-induced mastocytoma of DBA/2 mouse origin) or YAC-1 (Moloney leukemia-induced T-cell lymphoma of A/Sn mouse origin), but only against 203-glioma. It was found that the generation of Ts preceded that of CTL and that the turnover was faster; furthermore, Ts were generated in the thymus and spleen, while CTL were distributed in regional lymph nodes and spleen. Surface marker analysis revealed that only Lyt-1-.2.3+ T-cells participated in suppressor responses in contrast to both Lyt-1-.2.3+ and Lyt-1+.2.3+ T-cells participating in cytotoxic responses. The effects of adult thymectomy (ATx) on the changes of the immunized T-cell subsets were also investigated. In mice thymectomized 3 weeks previously, the Ts activity was abrogated, whereas the CTL activity increased markedly and Lyt-1+.2.3+ T-cells were not detected. The results suggest that CTL or their precursors bearing Lyt-1+.2.3+ phenotype and Ts bearing Lyt-1-.2.3+ phenotype are short-lived lymphocytes. Accordingly, it is suggested that in tumor-bearing mice short-lived Ts are generated earliest with target specificity and, due to the reciprocal relationships between Ts and CTL activities, may have a modulating influence on CTL; furthermore, ATx may alter the patterns of generation of the precursor T-cells and Ts.

Lack of detectable immunoglobulin E receptor expression on 33 of 34 cell lines with natural killer-like or cytotoxic-T-lymphocyte activity

We recently reported that a cloned murine cell line with "natural killer (NK)-like" cytolytic function and prominent cytoplasmic granules also expressed large numbers of plasma membrane receptors (Fc epsilon R) which bound mouse immunoglobulin E (IgE) with high affinity (S.J. Galli et al., 1982, Nature (London) 298, 288). We have now performed IgE-binding studies with 31 additional cloned murine cell lines exhibiting "NK-like" lytic activity (defined as the ability to kill YAC-1 lymphoma cells) and three antigen-specific cytotoxic-T-cell clones. One of the NK-like clones expressed a small number of Fc epsilon R (3.0 X 10(4)/cell) on one of the two occasions it was tested. None of the other clones, which were derived by several different approaches and which had a variety of surface glycoprotein phenotypes, expressed any detectable specific binding of mouse IgE. By contrast, mast cell clones consistently expressed large numbers of Fc epsilon R. The expression of large numbers of high-affinity Fc epsilon R would appear to represent a very uncommon characteristic of NK-like murine cell lines isolated under conditions similar to those described in this report.

Purification, chain separation and sequence of the MRC OX-8 antigen, a marker of rat cytotoxic T lymphocytes

The MRC OX-8 antigen is a marker of the rat cytotoxic T lymphocytes that consists of disulphide-linked chains of mol. wts. 37 and 32 kd. It is thought to be equivalent to the human T8 and mouse Lyt2,3 antigens (all now called CD8 antigens). MRC OX-8 antigen was purified from thymocytes using a monoclonal antibody column and because antigenicity was retained after reduction and alkylation the two polypeptide chains could be separated by a subsequent affinity chromatography step. Peptides were isolated from each chain and their sequences determined. A cDNA probe coding for the mouse CD8 antigen (pLY2C-1 provided by Dr L. A. Herzenberg) was used to obtain rat cDNA clones from which the sequence of the equivalent rat molecule was determined. Peptides from the 32-kd chain were identified in this translated sequence whereas peptides from the 37-kd chain were not. The 32-kd polypeptide sequence consisted of 210 amino acids and had one possible N-linked glycosylation site. The N-terminal part of the sequence was surprisingly different from both its mouse and human counterparts but, as in the other two species, it showed a clear relationship to Ig V domains.