Acquired pure red-cell aplasia: A consequence of increased natural killer cell activity?

A 19-year-old man with severe pure red-cell aplasia is described. An unusually high proportion of this patient's lymphocytes were large granular lymphocytes (LGL), both in the blood (40%) and in the bone marrow (50%). His blood leukocytes displayed a strongly elevated natural killer (NK) cell activity in vitro against the erythroblastic leukemia line K562. The patient's non-T blood lymphocytes inhibited in vitro erythroid colony formation (BFU-E and CFU-E) but not the granulocyte-monocyte colony growth (CFU-GM) from autologous and allogeneic bone marrow. Neither T-cell-mediated cytotoxicity nor circulating antibodies against erythroid precursors could be demonstrated. The patient's haemoglobin values returned to normal levels after three weeks of glucocorticoid treatment and have since then remained stable with continued prednisone administration. Attempts to reduce the prednisone dose to less than 10 mg/day have led to relapses. It is tempting to suggest that the patient's disease might be caused by hyperactivity of cytotoxic non-T (NK) cells specific for K562 cells and early erythroid precursors.     

Colony-forming assay for circulating chronic lymphocytic leukemia cells

In these studies, we report adaptation of a colony-forming assay to chronic lymphocytic leukemia (CLL) peripheral blood cells. T-lymphocyte-depleted CLL peripheral blood cells were cultured with irradiated, normal T cells and media conditioned by normal, mitogen-stimulated T cells in methylcellulose. Colonies containing small and transformed lymphocytes appeared after 5–7 days incubation. The plating efficiency of CLL colonies was 0.15 ± 0.08% ($\text{x}\text{±}\text{S.D.}$), similar to that of other colony-forming systems. The majority of CLL colony-forming cells were in S phase (50 ± 4%, $\text{x}\text{±}\text{S.E.}$) as determined by thymidine suicide and the fraction of colony-forming cells in S phase was inversely related to the WBC. Cells harvested from CLL colonies lacked surface markers for T lymphocytes and stained positively for monoclonal surface and/or cytoplasmic immunoglobulin light chains. A 1-h incubation was used to study the in vitro response of CLL colony-forming cells to adriamycin and melphalan. Preliminary studies suggest differences in patterns of in vitro sensitivity to melphalan between patients previously treated with alkylating agents and those who had not received treatment. This system can be used to study regulation of CLL cell proliferation, and may have utility in predicting response to chemotherapeutic agents.     

A fully human chimeric antigen receptor with potent activity against cancer cells but reduced risk for off-tumor toxicity

Chimeric antigen receptors (CARs) can redirect T cells against antigen-expressing tumors in an HLA-independent manner. To date, various CARs have been constructed using mouse single chain antibody variable fragments (scFvs) of high affinity that are immunogenic in humans and have the potential to mediate “on-target” toxicity. Here, we developed and evaluated a fully human CAR comprised of the human C4 folate receptor-alpha (αFR)-specific scFv coupled to intracellular T cell signaling domains. Human T cells transduced to express the C4 CAR specifically secreted proinflammatory cytokine and exerted cytolytic functions when cultured with αFR-expressing tumors in vitro. Adoptive transfer of C4 CAR T cells mediated the regression of large, established human ovarian cancer in a xenogeneic mouse model. Relative to a murine MOv19 scFv-based αFR CAR, C4 CAR T cells mediated comparable cytotoxic tumor activity in vitro and in vivo but had lower affinity for αFR protein and exhibited reduced recognition of normal cells expressing low levels of αFR. Thus, T cells expressing a fully human CAR of intermediate affinity can efficiently kill antigen-expressing tumors in vitro and in vivo and may overcome issues of transgene immunogenicity and “on-target off-tumor” toxicity that plague trials utilizing CARs containing mouse-derived, high affinity scFvs.     

Lysis of fresh human tumor cells by autologous large granular lymphocytes and T-lymphocytes: two distinct killing activities induced by coculture with autologous tumor

The specific and natural killer (NK)-restricted nature of autologous tumor killing by blood lymphocytes was studied in patients with carcinomatous pleural effusions. Large granular lymphocytes (LGL) and small T-lymphocytes were isolated by centrifugation on discontinuous Percoll density gradients. Tumor cells freshly isolated from pleural effusions of cancer patients were classified according to their susceptibility to purified LGL from normal donors in a 4-hour 51Cr release assay. Of 15 NK-sensitive tumors, 14 were lysed by fresh autologous LGL, whereas only 2 were killed by T-cells. Neither LGL nor T-cells were cytotoxic to NK-resistant autologous tumor. LGL and T-cells were then cultured in vitro with autologous tumor cells for 6 days. In 13 of 15 autologous mixed lymphocyte-tumor cultures (MLTC) NK-sensitive tumor-cultured LGL maintained their autotumor killing activity, whereas LGL cultured alone lost the activity. Depletion of high-affinity sheep erythrocyte-rosetting cells from Percoll-purified LGL resulted in an enrichment of effector cells. LGL from autologous MLTC were able to kill NK-susceptible allogeneic effusion tumor and K562 as were fresh LGL. No lysis of NK-resistant autologous tumor was observed with cultured LGL. In contrast, activation of T-cells in autologous MLTC resulted in the generation of autotumor killer cells in 10 of 15 NK-sensitive and 3 of 6 NK-resistant tumor samples. However, cultured T-cells were incapable of killing allogeneic tumor and K562. In autologous MLTC T-cells proliferated in response to autologous tumor, whereas no proliferation was observed in the culture of LGL. The enrichment of blasts from cultured T-cells on discontinuous Percoll gradients induced an augmentation of autotumor cytotoxicity, with no reactivity in blast-depleted, small, resting T-lymphocytes. These results indicated that 2 distinct types of autotumor-recognizing lymphocytes, LGL and T-cells, are present in the peripheral blood of cancer patients.     

Identification of a Human T Cell Clone with the Cytotoxic T Lymphocyte and Natural Killer-like Cytotoxic Function against Autologous Mammary Carcinoma and K562 Line

Pleural exudative lymphocytes (PLED from a 60-year-old female patient showed high cytotoxicity against the autologous mammary tumor line, HMC-2, and NK-susceptible K562 cells, although PLEL demonstrated only weak cytotoxic potentials against several allogeneic tumor lines. We successfully obtained seven cytotoxic T cell clones from PLEL bulk populations, and assessed the possibility that these lymphocytes are simply natural killer (NK)-like cells or have the dual cytotoxic activity of cytotoxic T lymphocytes (CTL) and NK-like cells. These clones, designated as T_cHMC-2, showed strong cytotoxicity against both HMC-2 and K562 cells. In contrast, allogeneic human peripheral blood-derived NK cells could not kill HMC-2 targets. Furthermore, a blocking study of T_cHMC-2 cytotoxicity using monoclonal antibodies against CD3, CD8 and human MHC class I products showed that all of these antigen molecules were involved in the cytotoxicity of T_cHMC.2 clone against autologous HMC-2 cells, indicating MHC class I recognitive cytotoxicity. These data indicate that the T_cHMC-2 clone may have dual cytotoxicity with CTL- and NK-like activity against autologous HMC-2 mammary tumor and K562 cells, respectively.     

Suppressive Activity of Interleukin 4 on the Induction of Antigen-specific Cytotoxic T Cells in Humans

The effect of interleukin 4 (IL 4) on the induction of cytotoxic T cells (CTL) was studied by using human peripheral blood lymphocytes in vitro. IL 4 suppressed the induction of CTL specific for allogeneic antigens in a concentration-dependent manner. However, IL 4 did not suppress proliferative responses induced with allogeneic antigens or mitogens. The suppressive effect of IL 4 on CTL induction was observed when IL 4 was added at the early period of the CTL induction culture, but not at the later period. Furthermore, IL 4 did not suppress the effector function of CTL to target cells. IL 4 suppressed the production of IL 1 by monocytes/macrophages and the production of IL 2 and the expression of IL 2 receptors on T cells. Moreover, IL 4 suppressed the induction of lymphokine-activated killer cells. These results suggest that IL 4 has a suppressive activity on the induction of killer cells in humans.     

Interleukin 2 activation of cytotoxic T-lymphocytes infiltrating into human metastatic melanomas

Tumor infiltrating lymphocytes (TIL) were isolated from 22 tumors obtained from 15 patients with metastatic melanoma. In 18 of the 22 tumors, a substantial number of lymphocytes was isolated with an average lymphoid cell:tumor cell ratio of 1.26. The TIL were predominantly cytotoxic/suppressor T-lymphocytes with an average of 87% Leu4+, 61% Leu2a+, and 18% Leu3a+ cells. There were less than 2% natural killer cells, B-cells, or macrophages. An average of 3.8% (range, less than 0.1 to 8.6%) of freshly isolated TIL bound to autologous tumor cells. Prior to culture, none of the tumor-binding cells (TBC) was cytotoxic as judged by trypan blue exclusion. The frequency of TBC increased to 11.6% after 2 days of culture, and 10% of these TBC developed cytotoxic activity. When interleukin 2 was added to cultures, the frequency of TBC increased, and the frequency of cytotoxic TBC was 2-fold higher compared to control cultures. After 10 days of culture with interleukin 2, TIL increased in number with a concomitant disappearance of tumor cells, whereas there were severe decreases of lymphocytes and no decrease of tumor cells in control cultures. TIL were cultured for 8 to 10 days with recombinant interleukin 2 and tested for cytotoxicity against autologous and allogenic tumor cells and K562 targets in a 4-h 51Cr release assay. rIL2-cultured TIL from all nine patients tested exhibited the highest levels of lysis against autologous tumor cells. Of the nine TIL samples, five exhibited an apparent specificity for autologous melanoma, while four specimens killed both allogenic and autologous melanoma. The ability of TIL to kill K562 targets appeared to parallel the ability to kill allogenic targets. For comparison, recombinant interleukin 2-cultured peripheral blood mononuclear cells from the same patients were assayed for cytotoxic activity against autologous and allogenic melanomas. Unlike some TIL, none of the peripheral blood mononuclear cells exhibited specificity for autologous tumor cells. In summary, TIL isolated from metastatic melanoma patients were predominantly cytotoxic T-lymphocytes with the ability to recognize and kill autologous tumor cells after in vitro culture; interleukin 2 induced proliferation of TIL and augmented their cytotoxic activity such that they eliminated autologous tumor cells.     

Functional analysis of mononuclear cells infiltrating into tumors: lysis of autologous human tumor cells by cultured infiltrating lymphocytes

Lymphocytes separated from surgically resected tumor tissue, uninvolved lung tissue, and peripheral blood of lung cancer patients were investigated for cytotoxic potential and analyzed for their phenotypes at the time of surgery and after having been propagated for 4 to 5 wk in the presence of interleukin-2. Most of the tumor lymphocyte infiltrates examined were shown to have a shift in favor of T8 subsets from those found in peripheral blood. No natural killer activity and low cytotoxicity against the autologous tumor were found to characterize the tumor-derived lymphocyte population. Propagation of lymphocytes from the different tissues of the cancer patient in the presence of interleukin-2 preparation induced widespread lytic activity against K562 cells, autologous and allogeneic tumors, but not autologous normal lung or lymphoblasts. However, cytotoxic activity against autologous tumor cells exerted by cultured tumor-infiltrating lymphocytes was found to be significantly higher than the activity of cultured lymphocytes isolated from peripheral blood or uninvolved lung tissue of the same patient. The elevated lytic activity of cells derived from the tumor tissue indicates the accumulation at the tumor site of precursors of natural killer-like cells and specifically stimulated antitumor effectors. Our results suggest the coexistence of two types of anti-autotumor cytotoxic lymphocytes at the tumor site: natural killer-like and specific cytotoxic T-cells.     

Inhibition of cytolytic T lymphocyte proliferation by autologous CD4+/CD25+ regulatory T cells in a colorectal carcinoma patient is mediated by transforming growth factor-beta

Cancer patients often develop CTLs that lyse autologous tumor cells in culture. However, tumors can progress in vivo despite the presence of CTLs. Various mechanisms have been reported to down-modulate CTL functions. In this study, the role of CD4+/CD25+ regulatory T cells in CTL induction and proliferation of established CTLs was investigated in a patient with CRC. CD4+ cytotoxic and regulatory T-cell lines were derived from the peripheral blood mononuclear cells of the same patient in mixed-lymphocyte tumor culture. The cytotoxic T-cell line and a clonal derivative specifically lysed the autologous tumor cells but not the B lymphocytes. Only HLA-A1-matched allogeneic CRC cells were lysed by the CTL clone. The clone produced IFN-gamma and TNF-alpha. The regulatory CD4+/CD25+ T-cell line was tumor cell-dependent in its growth but did not lyse autologous tumor cells. This T-cell line suppressed pokeweed mitogen responses of allogeneic lymphocytes, proliferative activity of the established, autologous CTLs, and induction of CTLs in autologous, freshly isolated peripheral blood mononuclear cells. The immunosuppressive effect of the CD4+/CD25+ regulatory T cells was mediated by transforming growth factor-beta and did not require cell-to-cell contact. Thus, although CRC patients can develop specific CTLs against their tumors, the development of regulatory T cells may allow the escape of tumor cells from immune surveillance by the CTLs in vivo.     

The Novel C24D Synthetic Polypeptide Inhibits Binding of Placenta Immunosuppressive Ferritin to Human T Cells and Elicits Anti–Breast Cancer Immunity In Vitro and In Vivo

Immune tolerance mechanisms supporting normal human pregnancy are exploited by breast cancer and other malignancies. We cloned from human placenta and breast cancer cells the novel human immunomodulator named placenta immunosuppressive ferritin (PLIF). PLIF is composed of a ferritin heavy chain–like domain and a novel cytokine-like domain, named C48. Both intact PLIF and C48 inhibit T cell proliferation. Blocking PLIF by specific antibodies in a tolerant breast cancer model in nude mice resulted in tumor cell apoptosis and rejection. This prompted us to study active immune preventive strategies targeting PLIF activity. Currently, we report on the design and synthesis of the novel C24D polypeptide, which inhibits the binding of PLIF to T cells and therefore inhibits the immune suppressive effect of PLIF. The effect of C24D on the generation of anti–breast cancer cytotoxic T lymphocytes (CTLs) was studied in vitro in cultures of MCF-7 (HLA-A2⁺) or T47D (HLA-A2⁻) breast cancer cells incubated with peripheral blood mononuclear cells (PBMCs) from healthy blood donors. We found that C24D treatment exclusively induced development of CTLs. On reactivation by their specific target cells, the CTLs secreted interferon-γ and induced target apoptosis. Anti–MCF-7 CTLs were cross-cytotoxic to MDA-MB-231 (HLA-A2⁺) triple-negative breast cancer but not to T47D. Moreover, C24D treatment in vivo inhibited the growth of MCF-7 tumors engrafted in immune-compromised nude mice transfused with naïve allogeneic human PBMCs. Our results demonstrate that C24D treatment breakdown breast cancer induced tolerance enabling the initiation of effective anti-tumor immune response.Abbreviations: CTLs, cytotoxic T lymphocytes; E:T, effector/target; FITC, fluorescein isothiocyanate; IFN-γ, interferon-γ; IL, interleukin; mAb, monoclonal antibody; PBMCs, peripheral blood mononuclear cells; PBS, phosphate-buffered saline; PLF, placental type isoferritin; PLIF, placenta immunosuppressive ferritin; TNBC, triple-negative breast cancer; TNF-α, tumor necrosis factor–α     

Human natural cytotoxic activity mediated by tumor necrosis factor: regulation by interleukin-2

Freshly obtained normal lymphoid cells kill certain tumor target cells in vitro. Using peripheral blood lymphocytes (PBLs) and the human tumor target cell line BT-20, we have defined a tumor necrosis factor (TNF)-dependent, cell-mediated cytotoxic mechanism that is homologous to the murine natural cytotoxic (NC) cell activity. Human NC cell activity was detected in freshly isolated PBLs and was augmented by short in vitro pulses with recombinant human interleukin-2 but not with recombinant human alfa interferon. Monoclonal anti-TNF antibodies inhibited the killing of the target cells. The independence of interferon and the mediation of killing by TNF distinguish human NC cell activity from natural killer and lymphokine-activated killer cell activities.     

Alemtuzumab (CAMPATH 1H) does not kill chronic lymphocytic leukemia cells in serum free medium

The mechanism of action of alemtuzumab (CAMPATH 1H) in chronic lymphocytic leukemia (CLL) is uncertain. We tested the hypothesis that alemtuzumab alone can induce apoptosis in cultured CLL cells. Purified peripheral blood B-lymphocytes from CLL patients were treated in serum free medium (AIM-V). There was minimal spontaneous apoptosis in untreated cells. Alemtuzumab ligation did not alter the membrane distribution of CD52 in single cells but many cells formed transient, small, tightly adherent clusters. Alemtuzumab alone did not induce apoptosis. In contrast, alemtuzumab plus complement was rapidly cytotoxic. We conclude that alemtuzumab does not cause apoptosis in purified CLL B cells cultured in serum free medium.     

Lysis of fresh human tumor cells by autologous peripheral blood lymphocytes and tumor-infiltrating lymphocytes activated by PSK

The protein-bound polysaccharide PSK was tested for the ability to induce in vitro autologous tumor killing (ATK) activity in human cancer patients. Peripheral blood lymphocytes (PBL) and tumor-infiltrating lymphocytes (TIL) demonstrated various levels of cytotoxicity against autologous, freshly isolated tumor cells. When PBL and TIL were cultured overnight with PSK, ATK activity was induced in previously non-reactive cases and augmented in previously reactive samples. The PSK effect was observed with PSK concentrations of 10-100 micrograms/ml that could be obtained in the blood of cancer patients who received standard oral administration of PSK. The manifestation of PSK-induced ATK required active cell metabolism and RNA and protein syntheses, but not DNA synthesis of lymphocytes. PSK-induced enhancement of ATK was not abrogated by monoclonal antibodies (mAb) directed against interferon (IFN) alpha or IFN gamma. In addition, mAb that neutralized interleukin-2 (IL-2) or mAb reactive with alpha-chain or beta-chain of IL-2 receptors (IL-2R) had no effect on PSK-induced ATK activity. Supernatants from PSK-stimulated lymphocyte cultures did not induce ATK. Cell fractionation experiments revealed that CD3-CD16+ large granular lymphocytes (LGL) and/or CD3+CD16- T lymphocytes were responsible for both spontaneous and PSK-induced ATK. PSK-activated LGL, but not T lymphocytes expressed lysis of fresh allogeneic tumor cells. These results indicate that PSK activates PBL and TIL to exhibit ATK independently of IL-2/IL-2R systems.     

T SUBSETS AND ANTITUMOR ACTIVITY OF LYMPHOCYTES INFILTRATING HUMAN PRIMARY BRAIN GLIOMAS

Glioma-infiltrating lymphocytes (GIL) were isolated from 9 surgical biopsy specimens of primary brain gliomas using mechanical and enzymatic digestion and discontinuous density gradent centrifugation. During cultured in the presence of interleukin-2 (IL-2) for a period of four weeks, GIL were expanded 48. 4-fold on the average, even up to 118-fold. GIL activated by IL- 2 had specific cytolytic activity against autologous glioma cells. Analysis of T subsets of GIL freshly isolated showed that CD3 cells were 71.0±11.9%, CD4 cells 34.2±6.1% and CD3 cells 37.0±7.6%. Ability of activated GIL to produce γ-Interferon (γ-IFN) was significantly higher than that of freshly isolated GIL and autologous peripheral blood lymphocytes (PBL). The results suggest that GIL have many advantages for an adoptive immunotherapy of patients with brain gllomas and be a new type of antitumor immune effector.     

Lysis of Fresh Human Tumor Cells by Autologous Peripheral Blood Lymphocytes and Tumor-infiltrating Lymphocytes Activated hy PSK

The protein-bound polysaccharide PSK was tested for the ability to induce in vitro autologous tumor killing (ATK) activity in human cancer patients. Peripheral blood lymphocytes (PBL) and tumor-infiltrating lymphocytes (TIL) demonstrated various levels of cytotoxicity against autologous, freshly isolated tumor cells. When PBL and TIL were cultured overnight with PSK, ATK activity was induced in previously non-reactive cases and augmented in previously reactive samples. The PSK effect was observed with PSK concentrations of 10–100 μg/ml that could be obtained in the blood of cancer patients who received standard oral administration of PSK. The manifestation of PSK-induced ATK required active cell metabolism and RNA and protein syntheses, but not DNA synthesis of lymphocytes. PSK-induced enhancement of ATK was not abrogated by monoclonal antibodies (mAb) directed against interferon (IFN)α or IFNγ-. In addition, mAb that neutralized interleukin-2 (IL-2) or mAb reactive with α-chain or β -chain of IL-2 receptors (IL-2R) had no effect on PSK-induced ATK activity. Supernatants from PSK-stimulated lymphocyte cultures did not induce ATK. Cell fractiona-tion experiments revealed that CD3^-CD16⁺ large granular lymphocytes (LGL) and/or CD3⁺CD16^- T lymphocytes were responsible for both spontaneous and PSK-induced ATK. PSK-activated LGL, but not T lymphocytes expressed lysis of fresh allogeneic tumor cells. These results indicate that PSK activates PBL and TIL to exhibit ATK independently of IL-2/IL-2R systems.     

Gamma delta T 细胞及其抗肿瘤研究的进展

Gamma delta（γδ）T细胞表达Vγ9Vδ2 T细胞受体,占外周血T淋巴细胞的2％～5％左右,主要分布于黏膜相关淋巴组织,是T细胞的亚群之一。其免疫作用介于固有免疫和适应性免疫之间,为主要组织相容性复合体（MHC）非限制性细胞, 具有一定的非特异性杀伤肿瘤细胞的作用,并且具有广泛的抗瘤谱。许多研究证实γδ T细胞参与了机体免疫防御系统的第一道防线,未来以γδ T细胞为基础的细胞免疫疗法,将会成为肿瘤免疫治疗的新战略。本文将对γδ T细胞的抗肿瘤作用机制及其临床应用作一综述。     

人外周血树突状细胞诱导及免疫学特性研究

[目的]从人外周血分离、纯化、扩增树突状细胞(DC),并对其形态学和免疫学特性进行初步探讨.[方法]从人外周血分离DC前体细胞(主要为CD14 细胞)用重组人粒细胞-巨噬细胞集落刺激因子(rhGM-CSF)和重组人白细胞介素-4(rhIL-4)联合培养,诱导扩增成熟DC.观察DC形态、分析DC表型、核型及检测DC激发同种异体淋巴细胞增殖能力.[结果]分离的DC前体经rhGM-CSF和rhIL-4共同培养1周后,可获得大量成熟DC,扩增了24.5倍,纯度达90%以上.DC高表达分化抗原CD86、CD40、HLA-DR、CD83、CDIa,能强烈激活同种异体T淋巴细胞增殖.[结论]人外周血CD14 细胞经体外诱导培养,可以生成大量功能成熟的DC,从而为进一步开展DC的基础研究和临床应用打下基础.     

骨髓瘤独特型抗原致敏树突细胞诱导的主动免疫反应

背景与目的:大多数多发性骨髓瘤(multiplemyeloma,MM)无法通过大剂量化疗和造血干细胞移植治愈,应用树突细胞(DCs)瘤苗清除MM患者化疗后残留的骨髓瘤细胞,是近年来骨髓瘤免疫疗法的新策略。本研究旨在探讨负载Id的DC独特型瘤苗对自体MM细胞的体外杀伤作用。方法:从MM患者外周血中分离获取DCs前体细胞,用GM鄄CSF与IL鄄4诱导分化,培养第5天加入从患者血清中提取的IgG的F(ab’)2片段(Id),第7天加TNF鄄α促成熟,将Id冲击致敏的DCs与自体T淋巴细胞共培养3天,获得肿瘤特异性细胞毒性T淋巴细胞(CTLs)。MTT法检测致敏DCs促自体T淋巴细胞增殖能力,以及患者CTLs对自体MM细胞的特异性细胞毒杀伤作用。结果:GM鄄CSF、IL鄄4和TNF鄄α联合可以有效地从MM患者外周血单核细胞中诱导出大量成熟的功能性DCs。MM患者自体血清Id冲击致敏的成熟DCs能够显著提高T细胞增殖能力,且与DC∶T的比值呈正相关;同时在1∶10时刺激细胞为负载了Id的成熟DC组刺激指数(SI)值(39.1±6.0)%,明显高于未经Id刺激的成熟DC组、经Id刺激的未成熟DC组以及未经Id刺激的未成熟DC组[(19.3±7.7)%、(15.9±6.1)%和(11.4±4.9)%]。负载了Id的成熟DC能够使幼稚T细胞活化成为肿瘤独特型CTLs,各个剂量的CTLs均能诱导出针对自体MM细胞的抑制性杀伤反应,并且     

Autologous mixed lymphocyte-tumor reaction and autologous mixed lymphocyte reaction. II. Generation of specific and non-specific killer T cells capable of lysing autologous tumor

The specific and non-specific nature of autotumor cytotoxicity induced in autologous mixed lymphocyte-tumor culture (AMLTC) and autologous mixed lymphocyte culture (AMLC) was studied in patients with carcinomatous pleural effusions. Small- and medium-sized blood lymphocytes that were isolated by centrifugation on discontinuous Percoll gradients did not lyse autologous, freshly isolated effusion tumor cells. In vitro activation of the small lymphocytes, but not of the medium lymphocytes, with autologous tumor cells generated cytotoxic potential restricted to autologous tumor. When stimulated with autologous non-malignant non-T cells, the medium lymphocytes, but not small lymphocytes, were triggered to cytotoxicity that acted not only on autologous tumor cells but also on allogeneic tumor cells, T blasts, and tumor cell lines. Experiments using monoclonal antibodies (MAb) and complement (C') showed that both types of killer cells were CD2+ CD3+ CD16- T cells. Autotumor cytotoxicity developed in AMLTC was mediated by the CD4- CD8+ T cell subset in 6 of 9 cases and the CD4+ CD8- subset in the other 3 cases. In contrast, cytotoxicity induced in AMLC was exerted exclusively by the CD8+ subset. The enrichment of blasts from cultured T cells on discontinuous density gradients enhanced autotumor killing activity, with no reactivity recorded for blast-depleted, resting T cells. Addition of mitomycin-C-treated large granular lymphocytes (LGL) to AMLTC abolished the induction of autotumor killer cells, whereas non-specific killer cells were generated in AMLC irrespective of the presence of LGL. These results indicate that stimulation of autoreactive T cells in AMLTC and in AMLC could induce 2 distinct types of autotumor killer cells.