Family of disulphide-linked dimers containing the zeta and eta chains of the T-cell receptor and the gamma chain of Fc receptors

Stimulation of T cells by antigen activates many signalling pathways. The capacity for this range of biochemical responses may reside in the complex structure of the seven-chain T-cell antigen receptor (TCR). In addition to the complexity shared by all TCRs, coexpression of zeta (zeta) and the distinct but related eta (eta) chains creates structural diversity among the TCR complexes expressed on a given cell. In most murine T cells that we have studied, about 90% of the heptameric receptor complexes contain a zeta zeta disulphide homodimer, whereas 10% contain a zeta eta disulphide heterodimer. Recent studies suggest that zeta has a critical role in allowing antigen to activate the cell, whereas eta expression has been correlated with the capacity for antigen-induced phosphoinositide turnover. A third zeta-related protein, the gamma (gamma) chain of the Fc epsilon and some Fc gamma receptors, exists as a disulphide homodimer in those complexes. The structural relatedness of zeta and gamma is emphasized by the recent demonstration of zeta zeta in association with CD16 in TCR-negative natural killer cells. Here we identify T cells lacking Fc receptors but coexpressing zeta, gamma, and eta, document the formation of novel heterodimers between zeta and gamma and between eta and gamma and show their association with the TCR. A greater range of homologous coupling structures than previously thought may be one way of achieving the variety of TCR-mediated (and possibly Fc receptor-mediated) biochemical responses and effector functions.

In vivo expression of perforin by CD8+ lymphocytes in autoimmune disease. Studies on spontaneous and adoptively transferred diabetes in nonobese diabetic mice

A potent cytolytic pore-forming protein (perforin or cytolysin) has previously been found to be associated with the cytoplasmic granules of CTL and NK cells. Inasmuch as all previous studies on perforin have been conducted with cultured CTL and NK cell lines, it is not clear whether perforin may play a role in the cytotoxicity mediated by CTL that have been primed in vivo. In this study, we investigated the presence of perforin in pancreata from nonobese diabetic (NOD) mice, which have been studied as a model of autoimmune, insulin-dependent (type I) diabetes mellitus. Whereas adult NOD mice spontaneously develop diabetes, it is possible to induce diabetes in young, irradiated NOD mice by adoptive transfer of splenocytes obtained from diabetic donors. By means of immunohistochemical analysis, we were able to detect perforin Ag in a small subpopulation of CD8+/Thy-1+/asialo GM1-/CD4- lymphocytes in the pancreatic islets of animals undergoing both spontaneous and adoptive transfer-mediated insulitis. Perforin+/CD8+ lymphocytes were found in small clusters and were observed to display the morphology of large granular lymphocytes. These observations show for the first time the presence of perforin-containing CD8+ lymphocytes in tissues of animals undergoing autoimmune disease.

Perforin mRNA in primary peritoneal exudate cytotoxic T lymphocytes

Considerable evidence indicates that cloned CTL cell lines kill target cells by releasing toxic granules that contain a cytolytic protein, called perforin, and several serine esterases (granzymes A to F). However, primary CTL, such as the highly cytolytic peritoneal exudate lymphocyte (PEL) cell population, have been found by a hemolytic assay to have no perforin, or perhaps only borderline levels of that protein, suggesting that these cells use a different lytic mechanism. To determine whether or not primary CTL express the perforin gene, we have here compared mRNA from PEL CTL and from a cloned CTL cell line, 2C, by Northern blot analysis using a perforin cDNA probe. CD8+ PEL CTL contain approximately 30% of the amount of perforin message present in 2C. Moreover, depletion of CD8+ T cells from the total peritoneal exudate cell population removes both cytolytic activity and perforin message. We have previously shown that PEL CTL elicit the same changes in target cells as cloned CTL cell lines and are resistant to lysis by the toxic granules purified from these cells lines. Taken together these results are consistent with the view that primary CTL, as well as long term cloned CTL cell lines, exercise their cytolytic activity by means of perforin.

Analysis of a monoclonal rat antibody directed to the alpha-chain variable region (V alpha 3) of the mouse T cell antigen receptor

Three rat mAb, RR3-15, RR3-16, and RR3-18, were established by fusing spleen cells from a rat immunized with the male Ag-specific cytolytic T cell clone, OH6, to mouse myeloma cells. The mAb was identified by their capacity to focus the cytolytic activity of the OH6 CTL clone on nonspecific target cells via FcR-FcR interaction. That all three mAb recognized the OH6 TCR was confirmed by immunoprecipitation studies in which each antibody precipitated a 90 kDa disulfide-linked heterodimer characteristic of the TCR. Surface immunofluorescence staining of a panel of T cell lines and splenic T cell populations showed that RR3-16 reacted not only to the OH6 T cell clone but also to a minor fraction of normal T cells. This reactivity was found to be due to the expression of a gene in the V alpha 3 family. However, RR3-16 did not react with all T cell lines and clones known to express genes from the V alpha 3 family. cDNA sequences of three independent RR3-16+ T cell hybridomas analyzed by polymerase chain reaction were identical to the previously published V alpha 3 sequence of the CTL clone C9. Thus, the mAb RR3-16 is specific for a single member of the TCR V alpha 3 gene family. Analysis of the expression of RR3-16+ TCR in CD4+ and CD8+ subsets of peripheral T cells demonstrated preferential expression on CD8+ T cells, suggesting regulated expression of this particular TCR V alpha gene.

Resistance of cytolytic lymphocytes to perforin-mediated killing. Murine cytotoxic T lymphocytes and human natural killer cells do not contain functional soluble homologous restriction factor or other specific soluble protective factors

CTL and NK cells produce a cytolytic pore-forming protein (perforin, cytolysin) localized in their cytoplasmic granules. These cytotoxic cells are resistant to killing mediated by other lymphocytes and by purified perforin. A membrane factor, known as homologous restriction factor (HRF), has been suggested to confer protection to different cell types against both C- and perforin-mediated lysis. The granules of human large granular lymphocytes have been reported to contain, in addition to perforin, a soluble HRF activity that can be eluted from anion-exchange columns at 115 mM NaCl. Here, we report that a soluble HRF activity is absent in the granules or the cytosol of murine CTL and human NK cells. Our data indicate that the inhibition attributed to HRF could be explained by exogenous EDTA added during granule fractionation. EDTA was shown to bind to Mono Q and to elute at 90 to 120 mM NaCl. A second perforin-inhibitory activity was also eluted from such a column. However, it was present in preparations obtained not only from CTL and NK cells, but also from some perforin-susceptible tumor cell lines, indicating that it has nonrestricted distribution and suggesting that it is probably irrelevant to the perforin-protection mechanism. Our results argue against a role for soluble granule HRF or other soluble factors in mediating resistance of cytotoxic lymphocytes against perforin-mediated lysis.

The absence of direct antimicrobial activity in extracts of cytotoxic lymphocytes

An important mechanism used by the immune system in resisting infections by intracellular pathogens is the destruction of host cells by cytolytic lymphocytes. Whether these lymphocytes display a more direct antimicrobial action remains unclear. We have attempted to answer this question by testing extracts of cytolytic lymphocytes, prepared by cell fractionation, against three bacterial species - Escherichia coli, Salmonella typhimurium, and Listeria monocytogenes. We also tested these extracts against two viruses - pseudorabies virus and vesicular stomatitis virus. The extracts showed negligible activity against the test organisms under the conditions used.

Generation and characterization of hamster monoclonal antibodies that neutralize murine tumor necrosis factors

mAb to murine TNF (MuTNF) were produced after immunization of Armenian hamsters with purified, Escherichia coli-derived rMuTNF-alpha. Antibody produced from clone TN3-19.12, was purified and was found to inhibit 100% of the lytic activity of either recombinant or natural MuTNF-alpha at an antibody input of 25 ng/U. TN3-19.12 also inhibited all the lytic activity in culture supernatants from a variety of T cell sources, including activated T cell clones and T cell hybridomas (all of which expressed high levels of TNF-alpha and TNF-beta (lymphotoxin, LT) mRNA). Western blot analysis was used to document the physical form(s) of MuTNF recognized by TN3-19.12. Recombinant and macrophage-derived TNF displayed identical patterns of a single band with Mr 17 kDa. In contrast, T cell culture supernatants exhibited patterns consisting of two bands with Mr 17 and 24.7 kDa. The higher m.w. form was glycosylated based on its sensitivity to n-glycanase and displayed a m.w. consistent with that of TNF-beta (LT). These data suggest that TN3-19.12 recognizes both MuTNF-alpha and MuTNF-beta (LT). Monoclonal TN3-19.12 and polyvalent rabbit anti-rTNF were used to establish a MuTNF-specific ELISA capable of detecting picogram quantities of recombinant or natural TNF. This assay was used to detect TNF in the sera of mice challenged with a lethal dose of LPS. Peak TNF serum levels of 11 ng/ml were observed in these animals 90 min after i.p. LPS administration and then rapidly declined to near base line levels by 3 h. These values were confirmed by quantitating levels of TNF functional activity in the same samples. TN3-19.12 injected into mice subsequently treated with LPS prevented the detection of TNF in the circulation by either assay and protected mice from the lethal effects of endotoxin shock. Thus, TN3-19.12 effectively neutralizes endogenously produced TNF in vivo.

Cytotoxic T lymphocyte clones from peripheral blood and from tumor site detect intratumor heterogeneity of melanoma cells. Analysis of specificity and mechanisms of interaction

CTL clones isolated from PBL or from tumor-infiltrating lymphocytes (TIL) of a melanoma patient (pt665) were screened for specificity on a panel including autologous tumor cells from two distinct metastases (Me665/1, Me665/2), autologous EBV-transformed B cells and 15 allogeneic cell lines of different histology. Each clone displayed a peculiar cytolytic activity ranging from lysis of most targets (PBL clone 4C4) to preferential reactivity on the two autologous metastases (TIL clone 8B3). Blocking and modulation experiments, revealed that the lysis of autologous-Tu cells by TIL clone 8B3, but not by PBL clone 4C4, could be inhibited by mAb to HLA-class I and to CD3 Ag or by CD3 complex modulation. Clone 8B3 was tested also on a panel of 25 tumor clones from Me665/2, revealing that only 4 neoplastic clones were lysed (2/4, 2/14, 2/17, and 2/51). Cold target competition experiments indicated that the uncloned autologous melanomas and one tumor clone (2/17), but no two other tumor clones (2/10, 2/15), could compete with one another for lysis by 8B3. Determination of melanin content of tumor clones from Me665/2 revealed that the four neoplastic clones recognized by 8B3 possessed much lower melanin levels than all the other 20 clones not lysed by this effector.

Identification and characterization of a membrane-bound cytotoxin of murine cytolytic lymphocytes that is related to tumor necrosis factor/cachectin

Cytotoxic T lymphocytes (CTLs) kill their targets by a contact-dependent mechanism. We investigated the possibility that the CTL membranes themselves could exert direct cytotoxic activity. Murine CTLs that had been fixed with paraformaldehyde retained a slow cytotoxic activity toward various target cells that are also sensitive to another cytokine, tumor necrosis factor (TNF)/cachectin. This cytotoxic activity was neutralized by antibodies specific for TNF. Membrane fractions obtained from CTLs were cytotoxic to TNF-sensitive targets but not to several TNF-resistant cell lines. Immunoblot analysis revealed a membrane protein band of 50-60 kDa from CTLs that reacts with anti-TNF antibodies. The surface localization of this cytokine was further ascertained by flow cytometry, indirect immunofluorescence, and immunoelectron microscopy studies using TNF-specific antibodies. Radioiodination of CTL surface proteins followed by immunoprecipitation with anti-TNF antibodies confirmed the presence of a TNF-related cytokine in the plasma membranes of CTLs that migrated with an apparent molecular mass of 50-60 kDa under disulfide-reducing conditions. This cytokine can be removed from membranes by treatment with detergents but not with high-salt buffers, suggesting that it may be an integral membrane protein.

Characteristics of cytotoxic thyroglobulin-specific T cell hybridomas

Clones of cytotoxic thyroid-specific T cell hybridomas were generated by fusion of thyroglobulin-primed, "in vitro"-boosted CBA lymph node cells with the AKR-derived lymphoma cell line BW 5147. One hundred and thirty one clones were obtained. Among them, 15 were able to induce the lysis of 51Cr-labeled syngeneic thyroid epithelial cells after 5 h of incubation at 37 degrees C. Two T cell clones, HTC1 and HTC2, were further studied. These clones, which exhibit cell surface characteristics of cytotoxic cells, were specific for only syngeneic thyroid cells (allogeneic thyroid cells or syngeneic epithelial cells were never lysed by these hybridomas). Moreover, by using Ag-pulsed syngeneic macrophages as targets, syngeneic cytotoxicity was shown to be specific for thyroglobulin and not for a nonrelated Ag. The lysis obtained with these autoreactive thyroid-specific T cell clones is restricted to class I major histocompatibility Ag. This property is assessed by both the blocking of syngeneic cytotoxicity toward thyroid epithelial cells or thyroglobulin-pulsed macrophages only by anti-class I mAb and by the detection of specific lysis of target cells exclusively when effector hybrid cells and target thyroid epithelial cells or thyroglobulin-pulsed macrophages shared at least class I major histocompatibility Ag.

[Cytotoxic molecules, perforin and serine esterase in cytotoxic T lymphocyte]

Cytotoxic T lymphocyte (CTL) contains two cytotoxic molecules, perforin and serine esterase, in its cytoplasmic granules. These molecules play a key role in CTL-mediated cell lysis, but the precise mechanism has not been fully understood. The author has discovered some of the biochemical characteristics of these cytotoxic molecules. The molecular weight of purified perforin was 66 kd under reducing conditions. Its activity was absolutely dependent on the Ca2+ concentration. The highest activity was seen at 0.2 mM Ca2+ concentration. The Zn2+ ion inhibited the perforin activity in the presence of Ca2+ ion. Heparin increased the pore-forming activity of perforin with highest stimulation at 400 ng/ml. The perforin inhibitor protein, having a molecular weight of 500 kd, was isolated from human serum. This inhibitor suppressed the membrane-binding activity of perforin. The CTL-specific serine esterase detected with the substrate BLT had a molecular weight of 66 kd determined by HPLC gel filtration. The author found that the localization of BLT serine esterase was distinct from that of perforin in CTL. A study into the significance of the difference in the localization of the two molecules is now in progress.

Maternal immune responses to the fetus in early pregnancy and recurrent miscarriage

Direct evidence that maternal immune rejection of the fetus causes some unexplained recurrent spontaneous abortions was sought in 18 women with this condition. Tests of maternal cell-mediated immunity to fetal (paternal) antigens were done before conception, in early pregnancy, and at miscarriage, and were compared with those in 10 controls in their first pregnancies. Maternal cytotoxic alloantibody production and the blocking effect of maternal sera on maternal lymphocyte activation were also evaluated. There was no evidence for maternal cell-mediated reactivity to paternal antigens in normal early pregnancy or in most women who aborted, but circulating cytotoxic cells were found at miscarriage in a third of affected women. There was no correlation between the production of cytotoxic antibodies and serum blocking activity, and the success of the pregnancy. These data provide evidence that cell-mediated immune reactivity may be changed in some women who abort recurrently but show that circulating immunological blocking factors are not relevant to the success of pregnancy. Their induction by maternal immunisation with paternal leucocytes does not explain why this procedure prevents recurrent spontaneous abortions.

Biotinylated recombinant interleukin-2. A tool for research on the interleukin-2 receptor

Recombinant interleukin-2 was biotinylated using a N-hydroxyl-succinimidyl [3H]biotin ester. The biotinylated lymphokine retained full binding and growth-promoting activities when assayed on the interleukin-2-dependent murine cell line HT-2. In preliminary studies, biotinylated interleukin-2 was used in conjunction with immunogold staining to demonstrate cell surface interleukin-2 receptors using both light and electron microscopy techniques. In addition, with rabbit anti-biotin antibodies, biotin-interleukin-2 was able to precipitate the 55 kDa IL-2 receptor from murine HT-2 cells. Thus, biotin-interleukin-2 represents a useful, non-radioactive tool for studying the structure and function of the interleukin-2 receptor.

Active specific immunotherapy for melanoma: phase I trial of allogeneic lysates and a novel adjuvant

A Phase I trial of active specific immunotherapy for melanoma was performed to measure the toxicity and immunological effects of the therapy. A mixture of mechanical lysates (homogenates) of two melanoma cell lines was injected together with a novel adjuvant, DETOX, into 22 patients. Several types of cell-mediated and humoral immunity to melanoma-associated antigens were measured serially. In the 17 patients with measurable disease, the sizes of lesions were also noted serially. At least six patients per group were injected s.c. with either 100, 200, or 400 antigenic units (approximately 10, 20, and 40 million tumor cell-equivalents) of the lysates mixed with 0.25 ml of DETOX s.c. on weeks 1, 2, 3, 4, and 6. Three patients at each dose level also received 300 mg/m2 of cyclophosphamide i.v. 4 days before the start of immunization. Evidence for successful immunization was obtained in 13 of the 22 patients. An increase in the frequency of peripheral blood cytolytic lymphocyte precursors reacting against melanoma cells occurred in 12 patients, as measured by a limiting dilution assay involving in vitro re-exposure to irradiated melanoma cells for 9-10 days. Eight of the 12 patients had received cyclophosphamide. By cold-target competition assays, these cytolytic lymphocytes appeared to be atypical T-cells, which recognized melanoma-associated antigens on several allogeneic lines without apparent major histocompatibility complex restriction. An increase in antibody titers against melanoma-associated antigens, measured by enzyme immunoassay, was found in five of 22 patients, and a change in delayed hypersensitivity against the melanoma lysate, in three patients. Responses were found at all three dosage levels of lysate, without an obvious dose optimum. No toxicity except minor local soreness was noted. Therefore, no maximum tolerable dose was defined. Five of 17 patients with measurable lesions had a remission of their melanoma, two complete and three partial, with three additional minor responses. A patient whose complete remission lasted 5.5 months, has no evidence of disease 22+ months after entry onto the study, with the aid of surgical resection of small s.c. recurrences on two separate occasions. Sites of regression included s.c. nodules, lymph nodes, and pulmonary nodules, with no responses in liver, adrenal gland, or bone. The patients who had an increase in cytolytic lymphocyte precursors comprised all eight with a clinical remission (five major, three minor). In contrast, none of the seven patients lacking an increase in cytotoxic lymphocytes had a clinical response.(ABSTRACT TRUNCATED AT 250 WORDS)

Fine mapping of an H-2Kk restricted cytotoxic T lymphocyte epitope in SV40 T antigen by using in-frame deletion mutants and a synthetic peptide

The CTL response to SV40 in C3H/HeJ mice is directed against the tumor (T) Ag and is H-2Kk restricted. CTL specific for both the amino terminus (residues 1-271) and the carboxyl terminus (residues 512-708) of the T Ag molecule have been detected, and we have previously cloned CTL of both specificities. In this paper we show that the panel of 10 CTL clones specific for the C-terminal region includes clones specific for three different epitopes, termed C1, C2, and C3. Epitopes C1 and C2 are conserved in the T Ag of the related papova viruses BK and SA12, and only epitopes C2 and C3 are present on SV40 transformed targets bearing the Kk mutant Kkml. Epitopes C1 and C2 were mapped to residues 563-576 by using in-frame deletion mutants of SV40 T antigen, and all clones specific for these two epitopes can lyse Kk bearing target cells in the presence of a synthetic peptide comprising residues 559-576. Kk and Kkml differ at residue 152, which is located in the Ag-binding pocket. Because epitopes C1 and C2 can be formed by the same antigenic peptide, but epitope C1 is not present on SV40 transformed Kkml cells, epitopes C1 and C2 must differ in the contribution made by residue 152 of the MHC class I molecule. These data show that CTL epitopes on transformed cells can be made up of Ag fragments, and strengthen the idea that this is a general phenomenon for both class I and class II restricted T cell epitopes.

Homology of perforin to the ninth component of complement (C9)

Perforin is one of the cytolytic factors present in the cytoplasmic granules of mouse cytotoxic T lymphocytes and natural killer cells. We have determined the sequence of the N-terminal amino acids of perforin purified from a mouse natural killer cell line, and, by using oligonucleotide probes corresponding to the amino acid residues, we have identified a complementary DNA encoding perforin from the cDNA library of a mouse cytotoxic T lymphocyte clone. As predicted from the functional similarities between perforin and the ninth component of the serum cytolytic system, complement (C9) (refs 4-8), the deduced primary structure of perforin has homology with C9 at their respective functionally conserved regions. We find that perforin is only expressed in killer cell lines, and not in helper T lymphocytes or other tumour cells tested. Thus we have provided direct molecular evidence that a killer-cell-specific protein evolutionally linked to C9 is involved in cell-mediated cytolysis.

Self-protection of cytotoxic lymphocytes: a soluble form of homologous restriction factor in cytoplasmic granules

A soluble form of homologous restriction factor (HRF) has been isolated from the cytoplasmic granules of human large granular lymphocytes that were cultured in the presence of recombinant interleukin 2 for 2-3 weeks. The granule-derived protein (approximately 65 kDa) is soluble in detergent-free solution and reacts with antibody produced to membrane HRF. HRF was first described as a 65-kDa membrane protein of human erythrocytes capable of inhibiting the formation of transmembrane channels by the membrane attack complex of complement. It has also been isolated from activated human lymphocytes and shown to confer upon these cells relative resistance to lysis by the membrane attack complex and by the complement component C9-related protein of human cytotoxic lymphocytes. The soluble HRF of lymphocyte granules inhibits reactive lysis of erythrocytes by the membrane attack complex of human complement. It was also found to be a potent inhibitor of (i) the cytolytic activity of the C9-related protein of human cytotoxic lymphocytes, (ii) human large granular lymphocyte cytotoxicity, and (iii) the cytotoxic activity of human CD8+ lymphocytes obtained by cell sorting from recombinant interleukin 2-activated peripheral blood mononuclear cells. It is proposed that granule-derived soluble HRF and cell surface-membrane-bound HRF are involved in the mechanism of self-protection of killer lymphocytes.

Measurement of cytotoxicity by target cell release and retention of the fluorescent dye bis-carboxyethyl-carboxyfluorescein (BCECF)

In order to utilize a newly available scanning microfluorimeter for lymphocyte-mediated cytotoxicity assays, a number of commercially available fluorescent dyes were compared for their suitability as target cell markers. One of them, bis-carboxyethyl-carboxyfluorescein (BCEFCF), was useful for assays with about 10(4) target cells and showed substantially less spontaneous leakage than other fluorescein derivatives, while still leaking more rapidly than 51Cr. For short cytotoxicity incubations (less than 2 h) with cytotoxic T lymphocytes (CTL), the corrected percentage BCECF release into the supernatant parallels that of 51Cr. For 4 h assays cytotoxicity could be quantitated by measuring the BCECF retained by target cells. Using human CTL and natural killer (NK) cells as effectors, with a variety of lymphoid cells and fibroblasts as targets in 4 h assays, the BCECF retention technique was found to give cytotoxicity values comparable to the 51Cr release assay. Cytotoxicity assays measuring BCECF fluorescence in microtiter wells with the scanning microfluorimeter offer advantages of safety, economy, and processing time compared with the 51Cr release assay.

A modified in situ enzyme-linked immunosorbent assay for quantitating interleukin-2 activity employing monoclonal anti-IL-2 receptor antibody

The IL-2R ELISA recently described by Igietseme and Herscowitz (J. Immunol. Methods 97 (1987) 123) is a simple and reliable procedure for measuring the immunological activation of lymphocytes based on the expression of the early activation antigen, the interleukin-2 receptor (IL-2R). In the present report, this assay has now been adapted for the quantitation of IL-2 in culture supernatants and is based on the measurement of augmentation of IL-2R expression resulting from the exposure of sensitive cells (IL-2-dependent T cell line, CTLL-2, and mitogenic blasts) to IL-2. Under the conditions of these experiments, the magnitude of IL-2R expression appears to be directly proportional to the concentration of IL-2 in a given sample up to an optimum concentration beyond which no further increase in IL-2R expression is observed. Dose-response curves revealed that the assay correlates well with the proliferative response of the responder cells as measured by the [3H]thymidine (3H-TdR) uptake assay which is the commonly employed assay for quantitating IL-2. Using a simple mathematical formula, units of IL-2 activity could be assigned to unknown IL-2 preparations employed in these studies based on the activity contained in a standard IL-2 preparation. In an attempt to further simplify the procedure, a novel approach involving an in situ assay was designed and was found to be applicable for quantitating IL-2 by both the 3H-TdR uptake assay and the IL-2R ELISA. The assay can provide direct information about the immediate effect(s) of ligand-to-receptor binding and/or the effect(s) of ligand on the initial response of the cell. The assay could be adapted to quantitate the interleukins, in general.

A high proportion of T lymphocytes that infiltrate H-2-incompatible heart allografts in vivo express genes encoding cytotoxic cell-specific serine proteases, but do not express the MEL-14-defined lymph node homing receptor

The role of cytotoxic cells in in vivo immune functions such as allograft rejection is unknown. To begin to assess the function of cytolytic cells in vivo we have begun with cytolytic cell-specific functional molecules: we have isolated and characterized cytolytic cell-specific cDNA clones from cytolytic T cell clones, both encoding distinct serine esterases. The HF gene encodes a trypsin-like enzyme while the C11 gene encodes an enzyme with likely specificity for acidic residues. Here we demonstrate, using in situ hybridization with RNA probe, that both genes are expressed selectively in a subset of T lymphocytes that have infiltrated cardiac allografts. The phenotype of these cells is consistent with the most frequent phenotype of active CTL raised in vitro: they are predominantly CD4-, CD8+, MEL-14- T cell blasts. Thus the expression of these genes, each of which encodes serine esterase found in killer cell granules in vitro, is a valid marker for these cells in vivo as well. The kinetics of their accumulation is consistent with, but not proof of, a putative role in allograft rejection. It is likely that HF and C11 gene expression will be of diagnostic value.

A rapid assay for measuring both colony size and cytolytic activity of limiting dilution microcultures

A combined 51Cr-release/MTT dye method is described for accurately measuring cytolytic activity and colony size in the same set of culture microwells. The method was applied to the study of cell-mediated lympholysis (CML) in limiting dilution analysis (LDA) cultures of human PBL from a renal transplant recipient and a healthy control. The results showed that the combined CML/MTT method could detect differences in lytic activity per cell in LDA cultures, and thus is a useful adjunct to standard precursor frequency analysis.

Clonal heterogeneity of HLA-B27 cellular allorecognition. Delineation of immunodominant sites

The fine specificity of nine cytolytic T lymphocyte (CTL) clones obtained after stimulation of HLA-B27- responder lymphocytes with B27.1+ lymphoblastoid cell lines has been analyzed. These clones defined three different reaction patterns when tested against a panel of target cells including those expressing all known HLA-B27 subtypes: (a) specific recognition of HLA-B27.1, B27.2 and B27d, (b) selective reactivity with B27.1, B27d and HLA-B40 and (c) selective recognition of B27.1, B27.2, B27d, B27f and B40. Representative clones within each group were analyzed in detail. Differences in lytic ability of the various susceptible targets within each group were established by cold target inhibition analyses and by blocking experiments with anti-CD3 and anti-CD8 monoclonal antibodies. When correlated with the known structure of the HLA-B27 subtypes, these results demonstrate the critical relevance of amino acid changes within residues 77-81 and at position 152 in modulating allospecific CTL recognition of HLA-B27.1 and suggest that these residues could be involved in the structure of immunodominant regions of this antigen. The observed cross-reactions with HLA-B40, differing from B27.1 in 16 amino acid residues, suggest that the simultaneous occurrence of multiple amino acid changes could have mutually compensatory effects, so that a cross-reactive epitope might result from various combinations of polymorphic residues.

Evidence for an association between CD8 molecules and the T cell receptor complex on cytotoxic T cells

The T cell differentiation molecule CD8 is thought to play an important role in class I major histocompatibility complex-restricted T cell activities but the precise function of this molecule is unknown. To explore this question, we have studied several CD3+, CD8+ class I alloantigen-specific cytotoxic T lymphocyte (CTL) lines and clones. The ability of these CTL to proliferate as well as to lyse specific targets was inhibited by either anti-CD3 or anti-CD8 monoclonal antibodies. Exposure of CTL to relevant but not irrelevant target cells induced the rapid (less than 1 hr) disappearance of approximately 20 to 30% of CD3 and CD8 molecules from the cell surface. The modulation of these molecules became maximal at 6 to 12 hr and recovered thereafter in parallel. Treatment of CTL with anti-CD8 prevented alloantigen-induced modulation of CD3, and treatment with anti-CD3 blocked modulation of CD8. Incubation of CTL with the combination of anti-CD3 and goat anti-mouse Ig also resulted in modulation of CD8. In contrast, the expression of other CTL surface antigens, such as CD2 (Leu-5, T11) and HLA-DR, was not reduced by any of these manipulations. These results suggest that CD8 molecules are associated with the CD3/antigen receptor complex on the surface of CTL, and may play a direct role in antigen-induced modulation and cross-linking of the T cell receptor.

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.