Specific and non-specific lymphocyte cytotoxicity in colon carcinoma

Generation of colon cancer-derived tumor-infiltrating T cells (TILs) for adoptive cell therapy

Adoptive cell therapy (ACT) using specific immune cells and stem cells has emerged as a promising treatment option that could complement traditional cancer therapies in the future. In particular, tumor-infiltrating lymphocytes (TILs) have been shown to be effective against solid tumors in various clinical trials. Despite the enormous disease burden and large number of premature deaths caused by colorectal cancer (CRC), studies on TILs isolated from tumor tissue of patients with CRC are still rare. To date, studies on ACT often lack controlled and comparable expansion processes as well as selected ACT-relevant T-cell populations. We describe a procedure for generating patient-specific TILs, which are prerequisites for clinical trials of ACT in CRC. The manufacturing and characteristics of these TILs differ in important modalities from TILs commonly used for this therapeutic approach. Tumor tissue samples were obtained from 12 patients undergoing surgery for primary CRC, predominantly with low microsatellite instability (pMMR-MSI-L). Tumors in the resected specimens were examined pathologically, and an approved volume of tumor tissue was transferred to a disposable perfusion bioreactor. Tissue samples were subjected to an automatically controlled and highly reproducible cultivation process in a GMP-conform, closed perfusion bioreactor system using starting medium containing interleukin-2 and interleukin-12. Outgrowth of TIL from tissue samples was initiated by short-term supplementation with a specific activation cocktail. During subsequent expansion, TILs were grown in interleukin-2-enriched medium. Expansion of TILs in a low-scaled, two-phase process in the Zellwerk ZRP bioreactor under hyperoxic conditions resulted in a number of approximately 2 × 10⁹ cells. The expanded TILs consisted mainly (73%) of the ACT-relevant CD3⁺/CD8⁺ effector memory phenotype (CD45RO⁺/CCR7^-). TILs harvested under these conditions exhibited high functional potential, which was confirmed upon nonspecific stimulation (interferon-γ, tumor necrosis factor-α cytokine assay).

Phenotype and function of T cells infiltrating visceral metastases from gastrointestinal cancers and melanoma: implications for adoptive cell transfer therapy

Adoptive cell transfer of tumor-infiltrating lymphocytes (TILs) can mediate cancer regression in patients with metastatic melanoma, but whether this approach can be applied to common epithelial malignancies remains unclear. In this study, we compared the phenotype and function of TILs derived from liver and lung metastases from patients with gastrointestinal (GI) cancers (n = 14) or melanoma (n = 42). Fewer CD3(+) T cells were found to infiltrate GI compared with melanoma metastases, but the proportions of CD8(+) cells, T cell differentiation stage, and expression of costimulatory molecules were similar for both tumor types. Clinical-scale expansion up to ~50 × 10(9) T cells on average was obtained for all patients with GI cancer and melanoma. From GI tumors, however, TIL outgrowth in high-dose IL-2 yielded 22 ± 1.4% CD3(+)CD8(+) cells compared with 63 ± 2.4% from melanoma (p < 0.001). IFN-γ ELISA demonstrated MHC class I-mediated reactivity of TIL against autologous tumor in 5 of 7 GI cancer patients tested (9% of 188 distinct TIL cultures) and in 9 of 10 melanoma patients (43% of 246 distinct TIL cultures). In these assays, MHC class I-mediated up-regulation of CD137 (4-1BB) expression on CD8(+) cells suggested that 0-3% of TILs expanded from GI cancer metastases were tumor-reactive. This study implies that the main challenge to the development of TIL adoptive cell transfer for metastatic GI cancers may not be the in vitro expansion of bulk TILs, but the ability to select and enrich for tumor-reactive T cells.

Identification of Lck-derived peptides capable of inducing HLA-A2-restricted and tumor-specific CTLs in cancer patients with distant metastases

The Lck protein (p56(lck)), a src family tyrosine kinase essential for T cell development and function, is aberrantly expressed in various types of cancers. We revealed recently that Lck can be a tumor antigen recognized by HLA-A24-restricted and tumor-specific cytotoxic T lymphocytes (CTLs) of cancer patients with metastases. In this study, we tried to identify Lck-derived epitopes capable of inducing HLA-A2-restricted and tumor-specific CTLs in cancer patients. The tumor-infiltrating lymphocytes (TILs) from 2 HLA-A2 cancer patients were found to respond to COS-7 cells when co-transfected with the lck gene and either HLA-A0201, -A0206, or A0207 cDNA. These TILs contained CTLs capable of recognizing either the Lck(61-69), the Lck(246-254), or the Lck(422-430) peptide among 24 different peptides, all of which were prepared based on the HLA-A2 binding motif. Importantly, in vitro sensitization with the latter 2 peptides induced tumor-specific CTLs in HLA-A2(+) cancer patients with metastases, but not in those without metastases. Overall, the Lck(246-254) and Lck(422-430) peptides could be useful for specific immunotherapy of HLA-A2(+) cancer patients, especially with distant metastases.

Recognition of the Lck tyrosine kinase as a tumor antigen by cytotoxic T lymphocytes of cancer patients with distant metastases

The Lck protein (p56(lck)), a src family tyrosine kinase that is essential for T cell development and function, is aberrantly expressed in metastatic colon cancers. p56(lck) seems to facilitate the malignant transformation of epithelial cells through initiation of anchorage-independent proliferation. We demonstrate that the lck gene encodes antigenic epitopes recognized by the HLA class I-restricted and tumor-specific CTL of metastatic cancer patients. Lck peptides augmented CTL activity in peripheral blood mononuclear cells (PBMC) of colon and other epithelial cancer patients with distant metastases, but not those without distant metastases. CTL precursors recognizing the Lck peptide were identified in freshly prepared PBMC of patients with distant metastases, and their frequency was significantly augmented by stimulation with the peptide. Thus, Lck peptides could be useful in developing a specific immunotherapy for cancer patients with distant metastases.

Infiltration of mononuclear inflammatory cells into primary colorectal carcinomas: an immunohistological analysis

Local immunoregulation mediated by mononuclear tumour-infiltrating cells is considered of importance for tumour progression of colorectal cancer, although the balance between immunosuppressor and cytotoxic activities is unclear. Colorectal cancers from 26 patients were investigated using a panel of monoclonal antibodies in order to identify subsets of mononuclear inflammatory cells and to study their pattern of distribution in relation to tumour stage and cytotoxic immune reactivity against the tumour. In all but five tumours, mononuclear cells, lymphocytes or monocytes were present in fairly large numbers, particularly in the stroma. The infiltration of CD4+ mononuclear cells predominated over the CD8+ subset. Infiltration near the tumour cells was found in four cancers only. Stromal infiltration of CD11c+ macrophages was found in all but eight tumours. Small regressive areas, in which the histological architecture of the tumours was broken down, were found in 17 tumours with intense or moderate infiltration by CD4+ lymphocytes or CD11c+ macrophages. Probably this destruction of tumour tissue was caused by cytotoxic activity of the tumour-infiltrating mononuclear cells. In Dukes' class A and B tumours, CD4+ lymphocytes predominated over CD4+ cells with macrophage morphology, but the latter were increasingly found in Dukes' class C and D disease. The occurrence of MHC II-positive macrophages and lymphocytes in different Dukes' classes was similar to that of CD4+ cells. In contrast to this, CD11c+ and CD11a+ cells were more frequent in Dukes' A and B class tumours compared with Dukes' C and D. Four out of nine tumours of the latter stages showed a poor inflammatory reaction. The interpretation of our results is that the subsets of tumour-infiltrating mononuclear cells change with advancing Dukes' class and that the local immune control is gradually broken down in progressive tumour growth, even if some cytotoxic activity is still present.

Immunologic dysfunction in cancer

The interactions between the tumor and its host are complex, and many aspects of the immune system appear to be adversely affected directly or indirectly by the presence of the tumor. Virtually all of the processes involved in immune induction and action have been implicated in the observed deficient response in tumor-bearing patients. Improved understanding and molecular analysis of the mechanisms underlying the escape of tumors from immune surveillance may lead to the development of novel strategies for the prevention of T-cell immunosuppression in cancer patients, the development of novel immunotherapeutic strategies, and potentially prevention of tumor progression or development.

Clinical significance of autologous tumor killing (ATK) activity and its induction therapy in human cancer

The activity of blood lymphocytes to kill autologous freshly isolated tumor cells tested at the time of surgery predicts a favorable clinical course in patients who have primary localized solid tumor and receive curative operation. The strong correlation of autologous tumor killing (ATK) activity with disease-free interval and total survival indicates that ATK activity is a meaningful prognostic indicator and provides evidence for immunological control of tumor growth and metastasis. Although there is no direct evidence that ATK lymphocytes play a critical role in regression of tumor and prevention of tumor regrowth, the lack of ATK activity in patients who relapsed and died may not result from other factors related to their poor performance status, immune functions and tumor characteristics. Clinical trials with ATK induction therapy resulted in an improvement of the clinical outcome in patients who naturally have no such potential. The data indicate that the presence of both natural and induced ATK activity is strongly associated with long-term survival. In addition, adoptive transfer of BRM-induced ATK effector cells resulted in prolongation of survival time even in patients with documented metastatic tumors. Thus, considerable emphasis should be placed on a strategy that induces ATK activity in vivo. Such an approach may provide a new focus for cancer immunotherapy.

Human colorectal tumour infiltrating lymphocytes express activation markers and the CD45RO molecule, showing a primed population of lymphocytes in the tumour area

This study investigated the phenotype of freshly isolated human tumour infiltrating lymphocytes (TIL) from 14 patients with colorectal tumours, and compared them with lymphocytes derived from the lamina propria of the unaffected mucosa and with lymphocytes derived from peripheral blood of the same patients. It was found that TIL expressed the activation markers CD25 and HLA-DR to a higher extent than the peripheral blood lymphocytes (p = 0.01), and that both lamina propria lymphocytes and TIL preferentially expressed the CD45RO + phenotype, associated with memory cells, in contrast with peripheral blood lymphocytes [corrected]. Both lamina propria lymphocytes and TIL contained few natural killer (NK) cells (CD3-CD56+) compared with peripheral blood lymphocytes (p = 0.001), and this was reflected in the cytotoxicity assays. After 1 to 2 weeks in culture with interleukin-2 100 U/ml, lymphocytes from all three compartments had a high cytolytic activity against all targets tested, consistent with the lymphokine activated killer cell phenomenon. No increase in the number of NK cells was noted after culture, but 20-30% of the T cells now coexpressed the CD56 molecule. This was most prominent in the CD8+ subset, but lymphokine activated killer cell activity was found in both CD4+ and CD8+ subsets. Possible tumour escape mechanisms are discussed.

Isolation and expansion of lymphocytes from gastrointestinal tumour tissue

Adoptive cellular immunotherapy (ACI) with tumour-infiltrating lymphocytes (TIL) has met with some success in patients suffering from malignant melanoma. However, the success of this approach hinges on the successful isolation and in vitro expansion of TIL. Viable, IL-2 responsive TIL were obtained from only two of five gastrointestinal primary or 'non-lymph node' secondary gastrointestinal tumours. In contrast, proliferating TIL were successfully expanded from four out of five lymph node secondary deposits from gastrointestinal cancer patients, but these TIL were non-cytolytic. Conversely, proliferating lymphocytes were generated from six out of seven malignant effusions from gastrointestinal cancer patients in the late phase of their disease. Despite the presence of effective anti-tumour cytotoxic activity in one such culture, these lymphocytes failed to proliferate sufficiently for potential clinical use. Consequent upon these findings, we are sceptical that ACI using mononuclear cells infiltrating primary or secondary sites from patients with gastrointestinal cancer will be feasible.

Biological significance of autologous tumor-killing activity and its induction therapy

The overall results presented in this review demonstrate that positive ATK activity at the time of surgery predicts a favorable clinical course in patients who have primary localized solid tumor and receive curative operation. The strong correlation of ATK activity with disease-free interval and total survival (a) indicates that ATK activity is a meaningful prognostic indicator and (b) provides evidence for immunological control of tumor growth and metastasis. According to these data, it is unlikely that cancer patients who remain tumor-free after 5 years of follow-up will develop recurrence or die from the disease. Although there is no direct evidence that ATK effector cells play a critical role in regression of tumor and prevention of tumor regrowth, the lack of ATK activity in patients who relapsed and died after surgery may not result from factors related to their poor performance status since no differences have been observed in background factors between ATK-positive and-negative groups. The prognostic value of ATK activity in patients with documented metastatic tumors has not been established yet. In this respect, however, the induction of ATK activity by BRM has positively correlated with prolonged survival time, while such a correlation is not observed with other parameters such as NK cells or LAK cell activity.

Based on the possible biological significance of ATK activity, clinical trials have been conducted to determine whether the induction of ATK activity before surgery by administration of BRM could improve the clinical outcome in patients who naturally have no such potential. The preliminary data indicate that the presence of both natural and induced ATK activity is strongly associated with longterm survival. Thus, considerable emphasis should be placed on a strategy that induces ATK activity in vivo. Such an approach may provide a new focus for cancer immunotherapy.

An analysis of autologous T-cell anti-tumour responses in colon-carcinoma patients following active specific immunization (ASI)

As part of a phase-II clinical trial of post-operative active specific immunization (ASI) with virus-modified autologous tumour cells (AuTu) in colorectal carcinoma patients, we have analyzed in vitro anti-AuTu immune responses with lymphocytes isolated from the peripheral blood (PBL) of 5 treated patients. The PBL of 3 "responder patients", those who developed a positive DTH reaction to AuTu, when stimulated in standard in vitro autologous lymphocyte tumour-cell cultures (ALTC), showed cytotoxic anti-AuTu reactivity only in association with natural-killer-cell(NK)-like activity. We removed nonspecific cytotoxic cells (CD56-positive) from PBL of colon carcinoma or melanoma patients and positively selected T cells with strong CD8 staining (CD8hi) using FACS. Following in vitro stimulation, specific cytotoxic T cells (CTL) directed against either autologous EBV-transformed B cells (AuEBV-B) or autologous melanoma cells were identified in the CD8hi T-cell population. However, even using this novel technique, no specific CTL against autologous colon carcinoma cell lines were detected in PBL from ASI-treated patients (2 DTH responders and 2 DTH non-responders). If AuTu-specific CTL precursors existed in these blood samples, their frequency must have been very low (less than 1 in 8 x 10(4) CD8 positive T cells). Sorted CD4 T cells from these patients, in the presence of autologous antigen-presenting cells, showed no specific anti-tumour proliferative response, and in one instance we observed inhibition of proliferation in the presence of tumour cells.

Antigen(s)-specific tumour-infiltrating lymphocytes from tumour induced by human herpes virus-6 (HHV-6) DNA transfected NIH 3T3 transformants

Tumour infiltrating lymphocytes (TIL) have recently been shown to mediate potent therapeutic effects in certain malignancies in mice and in humans. To understand the mechanism of TIL immunotherapy it would be advantageous to generate tumour-specific TIL and to study a defined system of TIL and target cells in which the tumour epitope(s) recognized by TIL might be identified. We have established tumourigenic cell lines by transfection of NIH 3T3 cells with the entire genome of human herpesvirus-6 (HHV-6) and its small fragment (about 5% of the viral DNA sequence). Injection of these cells into nude mice produced tumours termed G-2T and 14-2T, respectively. Cell lines derived from these tumours when injected in NIH Swiss mice produced tumours, G-2TS and 14-2TS, respectively. We have generated TIL from G-2TS tumour that can kill G-2TS tumour cells in vitro but not other related tumours (14-2TS or MCA-106). These TIL can be expanded between 2-6.5 every 3-5 days. The TIL proliferated in tissue culture in response to recombinant interleukin-2 and interleukin-4 and maintained their tumor specificity for up to 6 months in vitro. Their phenotype was Thy 1.2+, Lyt-2+ and L3T4-. The availability of such tumour-specific stable TIL lines and specific viral-transformed targets will provide an opportunity to characterize the tumour-associated antigen critical for the specific cytotoxicity in this system and thereby to clarify the mechanism of this promising immunological approach to cancer therapy.

Flow cytometric analysis of tumour infiltrating lymphocytes in breast cancer

In 31 patients with carcinoma of the breast the phenotype and activation status of tumour infiltrating lymphocytes (TILs) was analysed by flow cytometry. The predominant cells, in all patients, were T lymphocytes and in the majority of cases CD8+ (cytotoxic/suppressor) T lymphocytes were present in greater numbers than CD4+ (helper) T lymphocytes. There was no relationship between the degree of lymphocytic infiltration and either tumour stage or grade but there appeared to be an inverse correlation with the levels of oestrogen receptor (ER) in the tumour (P less than 0.01). Both populations of T cells had significantly higher numbers of cells carrying HLA DR (class II major histocompatibility antigen) than the equivalent populations in peripheral blood from the same patient group (P less than 0.001). The transferrin receptor was found on similar numbers of CD8+ T cells in peripheral blood and among the tumour infiltrating lymphocytes while more of the CD4+ T cells infiltrating the tumour were found to carry this receptor (P = 0.034). The Tac (CD 25) antigen was also on similar numbers of CD8+ T cells from both peripheral blood and the tumour but was on fewer of the CD4+ T cells in the tumour with respect to peripheral blood (P = 0.029). In both TILs and blood lymphocytes, the Tac antigen was consistently present on greater numbers of CD4+ T lymphocytes than on the CD8+ T lymphocytes (P less than 0.001) and as this is a component of the interleukin 2 (IL-2) receptor this may be of relevance to the use of IL-2 in TIL cancer therapy.

Expression of high-affinity IL-4 receptors on murine tumour infiltrating lymphocytes and their up-regulation by IL-2

Since interleukin-2 (IL-2) and IL-4 act in concert to support the development of cytotoxic T lymphocytes (CTL) and the generation of antigen-specific tumour infiltrating lymphocytes (TIL), we investigated the interaction of these cytokines with an established TIL line. TIL proliferated in an additive fashion in response to suboptimal concentrations of IL-2 and various concentrations of IL-4. TIL possessed high-affinity IL-4 receptors whether cultured in recombinant IL-2 (rIL-2) or rIL-4, but cells cultured in rIL-2 had higher numbers of IL-4 receptors than cells cultured in rIL-4. When TIL were cultured in increasing concentrations of rIL-2, a dose-dependent enhancement in IL-4 receptor number was observed. The maximum induction of IL-4 receptor expression was achieved by 4 hr of incubation with rIL-2 and was completely blocked by cycloheximide. Other cytokines, such as rIL-1, recombinant tumour necrosis factor (rTNF), recombinant interferon-alpha (rIFN-alpha) and rIFN-gamma, had no effect on IL-4 receptor number. rIL-2 also up-regulated IL-4 receptors on CTLL-2, a murine CTL line. These data indicate that high-affinity IL-4 receptors exist on murine TIL and they can be up-regulated by IL-2. Our observation that IL-2 up-regulates IL-4 receptor may help explain the additive effects of these lymphokines on the proliferation of TIL and other cell lines. It may also help explain their co-operative effects on the generation of antigen-specific TIL and the differentiation of CTL.

Effects of radiolabelled monoclonal antibody infusion on blood leukocytes in cancer patients

This study was undertaken to investigate the effects of a single infusion of radiolabelled murine monoclonal antibody (MAb) on peripheral blood leukocytes in cancer patients. Eleven patients with disseminated colon cancer, malignant melanoma, or lung adenocarcinoma were infused with 111In-labelled anti-ZCE 025, anti-p97 type 96.5c, or LA 20207 MAb, respectively. Blood samples were obtained before infusion, immediately after infusion (1 hr), and at 4 and 7 days postinfusion. Flow cytometry analysis of CD3+, CD4+, CD8+, CD16+, and CD19+ lymphocytes showed increasing CD4:CD8 ratios in seven patients after infusion. This phenomenon was not restricted to antibody subclass or to type of cancer. Two of the remaining patients exhibited a marked post-infusion increase in CD8+ cells. In all three patients with malignant melanoma, decreasing levels of CD16+ lymphocytes were noted after infusion and natural killer cell cytotoxicity showed fluctuations which paralleled the changes in the CD16+ subpopulation. Oxygen radical production by phagocytic cells was markedly affected in three subjects. These results suggest that a single infusion of radiolabelled murine MAb may alter the balance of critical lymphocyte subpopulations and modulate other leukocyte responses in cancer patients.

Association between invasiveness, inflammatory reaction, desmoplasia and survival in colorectal cancer

Five hundred and twenty seven colorectal carcinomas were reviewed histologically. A multivariate analysis (Cox) was used to test the prognostic importance of certain histological features (invasiveness, inflammatory reaction, and amount of fibrous tissue) at the tumour edge after allowance had been made for clinicopathological stage, tumour site, and histological type and grade. A poorly defined tumour border, lack of inflammatory reaction, and a pronounced fibrosis (desmoplasia) at the tumour edge were associated with unfavourable stage distributions, but each of these features also had an independent effect on prognosis.

Morphometric and morphologic evaluations in stage III non-small cell lung cancers. Prognostic significance of quantitative assessment of infiltrating lymphoid cells

This study evaluated data from 30 non-small cell lung cancer (NSCLC) patients to determine whether demographic, clinical, and morphologic and morphometric data that were obtained prior to treatment, could be used to predict survival. All patients had Stage III disease, and all subsequently were treated identically with concurrent radiotherapy, cisplatin, and 5-fluorouracil. The series consisted of 18 squamous carcinomas, eight adenocarcinomas, and four large cell carcinomas. Morphometric measurements of randomized selected cancer cells per case included diameter of cytoplasm, nuclei, and nucleoli. Morphologic parameters evaluated were mitotic index, histologic differentiation, and pattern of nuclear chromatin of cancer cells, and the degree of necrosis and fibrosis of tumor tissue. The lymphoid and neutrophil index defined as the ratio of lymphoid cells and neutrophils to cancer cells from randomized microscopic fields (median = 25) at 400 x magnification were also determined. Our study indicated that the peritumor lymphoid index was the only factor significantly associated with the length of survival. The correlation coefficient (Pearson r) of these two factors was 0.5 (P less than 0.005). The median survival time of patients with peritumor lymphoid index less than 3 and greater than or equal to 3 was 95 days and 376 days, respectively (Kaplan-Meier estimation). The peritumor lymphoid index was an independent prognosticator of clinical outcome of Stage III NSCLC patients, and did not correlate with any of the other parameters analyzed.

Natural killer and lymphokine-activated killer cell-mediated cytotoxicity in patients with oral cancer

Peripheral blood lymphocytes (PBL) from untreated and treated oral cancer patients, lymph node lymphocytes (LNL) from metastatic (met) and nonmetastatic (non-met) lymph nodes, and tumor infiltrating lymphocytes (TIL) were tested for natural killer (NK) and lymphokine activated killer (LAK) cell cytotoxicity using appropriate targets in a short-term chromium release assay. The results showed that while both NK and LAK functions of PBL from oral cancer patients were comparable to those of normal healthy donors, the NK activity of metastatic and nonmetastatic LNL and TIL was highly compromised. On the other hand, potent LAK activity could be generated from all three lymphoid populations. Individual patients showing low NK activity displayed good LAK cytotoxicity, indicating that endogenous cells with low NK potential have adequate ability to respond to interleukin 2 (IL-2). LAK activity tested on autologous tumour targets revealed that TIL were the best source of LAK cells. followed by PBL and LNL.

Depressed level of natural killer cells in cancer family syndrome

Individuals from kindred with cancer family syndrome (CFS) have an increased genetic risk for the development of adenocarcinoma of the colon as well as of several other organs. Previous studies have suggested that this high occurrence of adenocarcinoma in this as in other hereditary neoplastic syndromes may be correlated to an underlying abnormality in immunological tumor surveillance. In attempt to define a marker that might identify individuals within CFS kindred at risk of developing cancer, we determined natural killer (NK) cell number and NK cell function in affected and healthy members of a CFS family. We studied 13 cancer-affected patients, 20 unaffected but "at-risk" subjects, 20 healthy subjects and 26 normal individuals matched to the patients with colon cancer on the basis of sex and age. We determined the number of NK cells and their function concurrently, using a monoclonal antibody and a 51Cr-release assay with K562 as target cells. We found that the number of NK cells was significantly (P = 0.00004) reduced in cancer patients as compared with healthy subjects and normal controls. Of the 20 at-risk individuals 9 had levels lower than the norm, while 11 showed normal-values. Consequently, the mean percentage of NK cells of this group does not differ either from that of normal subjects or from that of cancer patients. Mean NK cell function was lower in cancer patients than in healthy members of the CFS family but the differences were not statistically significant. Therefore, the mean NK cell function per single cell, expressed as a ratio between cytotoxicity (LU) and the number of NK1-positive cells, resulted paradoxically in an increase when compared with that of normal subjects. The possible mechanisms for this dichotomy were examined.

Impaired local natural killer cell activity in human colorectal carcinomas

The present study was undertaken to study natural killer (NK) cell activity in patients with colorectal cancer at peripheral and local levels. Mononuclear cells were isolated from uninvolved colorectal mucosa, tumor tissue and peripheral blood, and tested against the colon carcinoma cell line CaCo-2 and the erythroleukemia cell line K-562. Peripheral blood NK cell activity from the patients showed similar levels compared with healthy controls, whereas, mononuclear cells of tumor tissue were found to have a significantly decreased NK cell activity compared to the normal intestinal mucosa (P less than 0.01). No relation was found between the NK cell activity and the advancement of the disease according to the Duke's stage. Interferon-gamma (IFN-gamma) stimulated the NK cell activity of the mononuclear cells from blood, mucosa and tumor. However, the increase of NK cell activity after IFN-gamma stimulation was lower in the tumor compared to the mucosa (P less than 0.02). The lectin, phytohaemagglutinin, increased the cytotoxicity of mononuclear cells from blood, mucosa and tumor to a similar level. These results suggest that patients with colorectal tumors exhibit a normal NK cell activity in peripheral blood and intestinal mucosa; however, a diminished NK cell activity exists at the tumor level. Although mononuclear cells isolated from the tumor have a normal response to lectin stimulation they show hyporesponsiveness to IFN-gamma stimulation with regard to their NK cell activity.

Tumour-associated proliferative responses in vitro of regional lymph nodes draining solid cancers in man

The proliferative responses in vitro of tumour-draining lymph node lymphocytes were evaluated against autologous colon and lung carcinoma cells. The reactivity of lymphocytes appeared to be directed against tumour-associated rather than tumour-specific antigens. The lymphocyte reactivity detected was not due to an autologous mixed lymphocyte reaction. Recombinant interleukin-2 augmented the responses detected but not their tumour specificity. Phenotypic characterisation indicated the presence of T suppressor/cytotoxic (TS/C) cells as well as natural killer (NK) cells. Only the later, however, were active in functional cytotoxicity assays. The inability to generate both tumour-specific proliferation of tumour-draining lymph node lymphocytes and tumour-specific cytotoxic killer cells may be due to the presence of suppressor cells in the regional lymph nodes; preliminary data suggest the presence of such cells.

Antitumor activity of regional lymph node lymphocytes in patients with lung cancer

Cytotoxic activities of regional lymph node lymphocytes (RLNL) and peripheral blood lymphocytes (PBL) of 49 primary lung cancer patients who were subjected to surgical resection were examined by 4 h 51Cr release assay. PBL showed significantly lower cytotoxicity against autologous tumor cells than against K562 and QG-56. On the other hand, RLNL exhibited the same level of cytotoxicity against autologous tumor cells as PBL, although the cytotoxicities against K562 and QG-56 were low. Cytotoxicity of RLNL against autologous tumor cells exhibited a significant degree of depression with the advance of stage, T and N factors. Cytotoxicity of PBL did not significantly change as the stage progressed. When both PBL and RLNL were cultured with purified interleukin-2 (p-IL2) in vitro, their cytotoxic activities were markedly augmented and the cytotoxicities could not be diminished by the treatment with anti-Leu-7 + anti-Leu-11b + C'. These facts indicate that the augmented cytotoxicity may be due to lymphokine activated killer (LAK) cells.

Expansion of human tumor infiltrating lymphocytes for use in immunotherapy trials

The potential utility of tumor-infiltrating lymphocytes (TIL) in the adoptive immunotherapy of human tumors has been suggested by murine experiments showing these cells to be 50-100 times more powerful than LAK cells in treating advanced metastatic disease. A method for the large-scale expansion of human TIL for the use of these cells in clinical trials is described in this report. TIL were successfully expanded on an experimental scale from 24 of 25 consecutive human tumors, including six melanomas, ten sarcomas, and eight adenocarcinomas. Tumors were digested enzymatically to yield single cell suspensions which were cultured in RPMI 1640 medium with 10% human serum and 1000 U/ml recombinant interleukin-2. Lymphocytes constituted from 3% to 74% of single cell tumor suspensions, and expanded from 2.9-fold to 9.1 X 10(8)-fold over a culture period ranging from 14 to 100 days. Nine of 24 TIL cultures lysed fresh autologous tumor targets in 4 h chromium release assays. Cell surface phenotyping identified cultured TIL as activated cytotoxic/suppressor T cells. Subsequently, large-scale expansion of TIL was successful in generating more than 10(10) lymphocytes in five of eight consecutive cases. Clinical trials employing the adoptive transfer of expanded TIL to patients with metastatic disease have begun.

Potential impact of immunobiotechnology on cancer therapy

Genetic engineering techniques allow large scale production of substances generated during the immune response and these may have therapeutic value by modifying the biological response to cancer.

Morphological and functional characteristics of mouse mammary carcinoma cells separated on Nycodenz columns

Tissue from four mouse mammary carcinomas was enzymatically disaggregated and cells from the resulting cell suspension were fractionated on a discontinuous density gradient column (5-20%) of Nycodenz (Nycomed A.S. Oslo). The cell fractions separating at the 10-15% and 15-20% interfaces (density 1.082 and 1.110 g/ml respectively) contained a mean of 83.2 +/- 10.8 (s.d.) and 79.9 +/- 17.4 tumour cells. Compared with the original cell suspension these cell bands contained less cell aggregates and cell debris. The cells in the bands also showed an equivalent ability to grow in tissue culture and to form pulmonary tumours on i.v. injection into isogenic mice, when compared with the tumour cells in the original suspension. The relatively pure preparations of carcinoma cells thus separated may be of value in limiting the unwanted effect of normal cell contamination when testing neoplastic cells in vitro for sensitivity to drugs or hormones.

Natural cytotoxicity in draining lymph nodes of squamous cell cancer in the maxillofacial region

There is at present very little information available, including the presented preliminary data, concerning NK activity in patients with head and neck cancer. The objective of the present investigation was to study NK activity in peripheral blood (PB) and regional lymph nodes (LNs) in patients with different stages of head and neck cancer. Furthermore, phenotypic characterization of lymph node cells was performed. Finally, the in vitro response of mononuclear cells isolated from blood and lymph nodes to interferon was investigated.

Activation of lymphocyte anti-tumour responses in man: effector heterogeneity and the search for immunomodulators

Data continues to accumulate on the immunological reaction against solid human cancers. The evidence at the present time supports the view that rather than being immunologically invisible, tumour cell antigens are recognised by at least three lymphocyte subsets. Helper T cells can be induced to proliferate upon exposure to cells of the autologous tumour and to secrete detectable levels of interleukin 2 (IL-2). Cultured T cell lines and clones can be shown to respond in primed lymphocyte tests not only to autologous tumour cells but also to allogeneic tumour cells of the same histology and anatomic location. Cytotoxic T cells manifest specific reactivity against cells of the autologous tumour which is distinguishable from natural killing (NK) on the basis of specificity and organ distribution. Natural killer cells can lyse freshly isolated autologous tumour cells after purification on Percoll gradients or when activated by IL-2. There is thus a demonstrable heterogeneity of response to human cancer in unseparated lymphocyte populations and at the clonal level. In limiting dilution assays lymphocytes at the tumour site respond more frequently to autologous tumour relative to NK targets. For at least some tumours there is evidence that the expression of auto-tumour reactivity but not NK correlates with the clinical course of the disease and is a favourable prognostic indicator. The finding of these auto-tumour reactivities has important implications for the search for immunomodulating drugs for cancer treatment. However, it must be recognised that the response is heterogeneous and that the immune system comprises multiple interactive elements that exhibit both positive and negative control. Any treatment modality must take this into account and seek to focus on specific activation of the tumour lytic populations or the inhibition of negative regulatory elements as opposed to seeking a more general augmentation of immune reactivity which may, by stimulating suppressor cells, have a counterproductive effect.

In vitro generation of tumour-specific lymphocyte reactivity to colonic carcinoma cells. Comparison with normal colonic mucosa cells

Purified tumour cells and normal mucosa cells from fresh human colorectal cancer resection specimens, and T-cell-enriched autologous peripheral blood lymphocytes, were mixed in short-term (6 day) mixed lymphocyte-tumour cell (MLTC) microcultures. Lymphocyte stimulation was measured by 3H-thymidine uptake, and a stimulation index (SI = [lymphocytes vs tumour cells (cpm)-tumour cells (cpm)]/[lymphocytes (cpm)] greater than 3 was regarded as significant. Significant lymphocyte reactivity was found in 10/15 patients with colon carcinoma. However, 1 patient with autologous tumour reactivity, also showed significant stimulation against autologous normal mucosa cells, suggesting tumour-associated reactivity. Maximum stimulation occurred most frequently at a lymphocyte:tumour cell ratio of 2:1 and with nylon wool-passaged lymphocytes.

Systemic and regional natural cytotoxicity in patients with head and neck cancer

Forty patients with squamous carcinoma of the oral cavity (head and neck cancer) were investigated for natural killer-cell (NK) activity in peripheral blood (PB) and tumour-draining lymph nodes (LNs). For measuring NK activity a 4 hrs 51Cr release assay and K 562 target cells were used. Mononuclear cells of PB (PBMNC) and LNs (LNMNC) were separated by Ficoll Hypaque gradient centrifugation. NK activity was determined before tumour surgery. LNs were obtained either at the time of surgery of the primary tumour (en bloc neck dissection)--"immediately dissected LNs (ID-LNs)" or some time after removal of the primary tumour, especially for prophylactic purposes,--"delayed dissected LNs (DD-LNs)". Preoperatively, NK activity was clearly stage-dependent, patients with stages T1-2 displaying mean values similar to those of a control group without malignant disease, whereas values were significantly lower in patients with stages T3-4. Spontaneous cytotoxicity was significantly lower in LNMNC than in PBMNC of identical donors. NK activity was significantly lower in ID-LNs than in DD-LNs. These results suggest some negative influence of the primary tumour in the spontaneous cytotoxicity in both PB and tumour-draining LNs. In vitro incubation at +37 degrees together with addition of lymphoblastoid interferon (IFN-alpha) achieved a significantly stimulation of NK activity in both PBMNC and LNMNC.

Lysis of autologous tumor cells by blood lymphocytes tested at the time of surgery. Correlation with the postsurgical clinical course

Lymphocyte-mediated lysis of autologous tumor cells (autologous lymphocyte cytotoxicity ALC) was tested at the time of surgery in 108 patients (46 squamous cell carcinomas of the lung, 25 adenocarcinomas of the lung, 19 soft tissue sarcomas and 18 osteosarcomas). The clinical course of these patients in relation to the test results has been published previously. The group was evaluated again after an extended observation time, now with a mean of 80.2 months (range 36-108). The test was rarely positive in patients with metastasis (2 out of 28 experiments). There was a correlation between the ALC results and the postsurgical clinical course for patients without detectable metastasis in that (1) a negative test was invariably a bad prognostic sign, i.e., all 32 patients with negative ALC died within 3 years (mean survival time 16.1 months). (2) The remission and survival times were longer for the ALC positive patients (p less than 0.001). (3) All 37 individuals who are alive at present without recurrence belong to the reactive group. The ALC results correlated with the clinical course in 88% of patients. The correlation was highest for the groups of soft tissue sarcoma and adenocarcinoma of the lung. There was no correlation between killing of K562 cells and ALC, or between lymphoproliferative response to PHA and ALC reactivity.

An enzymatic method for the consistent production of monodispersed viable cell suspensions from human solid tumors

An enzymatic method is described for disaggregation of viable tumor cells from human solid tumors. The enzymatic cocktail consists of 0.1% collagenase, 0.01% hyaluronidase, and 0.002% deoxyribonuclease. After mechanical mincing of the tumor tissue, tumor specimens are dissociated by incubation in the enzymatic cocktail for 12-18 hours at room temperature. In 17 cases of sarcoma, the mean yield was 5 X 10(6) viable cells per gram tumor tissue. Yield was 1 X 10(7) viable cells per gram tumor tissue in 23 cases of gastrointestinal carcinoma. The viabilities of tumor cell suspensions ranged from 50 to 98%, except for low viabilities in four specimens that were grossly composed almost entirely of necrotic tissue. The dissociation procedure is simple and the viable cell yield is sufficient for applications in studies of human cancer immunobiology.

The use of VEP13 monoclonal antibody for definition of natural killer cells: spontaneous killer cells directed against fresh human leukaemia cells carry the VEP13 antigen

VEP13, an IgM monoclonal antibody (MoAb), produced against human large granular lymphocytes, is able to deplete natural killer (NK) cell activity in complement-dependent lysis. Here we report that VEP13 also reacts with the majority of interferon (IFN) activated NK cells. By contrast cytotoxic activity of unstimulated monocytes and cytotoxic T cells directed against allogeneic lymphocytes were unaffected by VEP13 plus complement treatment. Thus among the major types of cytotoxic cells VEP13 selectively reacts with NK cells and hence can be employed to identify these cells. We therefore used VEP13 in complement-dependent lysis and FACS separation to analyse NK cells involved in enhanced killing of fresh leukaemia cells. Spontaneous cell-mediated lysis of human leukaemia cells was enhanced in two ways: (a) effector cells were pre-treated with beta-IFN and (b) leukaemia cells were pre-treated with a pulse of actinomycin D. In complement-dependent lysis VEP13 removed all NK cell activity of IFN activated PBM against untreated and against ActD pre-treated leukaemia cells. FACS separation of VEP13 positive cells further supported this finding, in that all activity of IFN activated NK cells against actinomycin D pre-treated targets was found in the VEP13 positive fraction. Thus enhanced killing of fresh human leukaemia cells appears to be mediated VEP13 positive NK cells which are distinct from cytotoxic T cells and cytotoxic monocytes.

Distribution of histocompatibility and leucocyte differentiation antigens in normal human colon and in benign and malignant colonic neoplasms

Monoclonal antibodies (McAbs) directed against the framework determinants of Class I and Class II products of the major histocompatibility complex (MHC) and against leucocyte differentiation antigens were used in an indirect immunoperoxidase technique to study their expression in normal, benign (adenomatous polyps) and malignant disease of the colon. Class I products (detected by the McAb 2A1) were strongly expressed on all cell types in normal and benign tissues but some carcinomas exhibited a heterogenous pattern of epithelial cell staining and 4/15 were completely negative. Class II products (detected by TDR31.1) were strongly expressed on cells (mainly B lymphocytes) within the lamina propria. In carcinomas TDR31.1 staining was mainly interstitial, but in 2/15, DR + epithelial cells were also detected. In normal and benign tissues, leucocytes (reactive with 2D1) found predominantly in the lamina propria, comprised T cells mainly of the helper/inducer (OKT4) subset, DR + cells in approx. equivalent proportion and a few OKM1+ cells mostly of macrophage morphology. Occasional intraepithelial lymphocytes were of cytotoxic/suppressor (OKT8) phenotype. In malignant neoplasms, there was wide inter and intra-tumour variation in the proportion of leucocytes which were heterogeneous with respect to cell type and confined mainly to the stroma. T cells were consistently predominant, but B cells and macrophages were also present. Two neoplasms showed unequivocal evidence of a shift (relative to peripheral blood) in favour of the OKT8+ subset, but in the majority of tumours OKT4+; and OKT8+ cells were present in roughly similar proportions. Natural killer cells (monitored with Leu7, HNK1) were virtually undetectable in both normal and malignant tissues. There were no apparent correlations between the extent and type of leucocyte infiltration, tumour differentiation or expression of MHC products. Some implications for the extrapolation of in vitro data on leucocyte function to the in vivo situation are discussed.

Immunomodulation: NK cells activated by interferon-conjugated monoclonal antibody against human osteosarcoma

A mouse monoclonal antibody raised against the human osteogenic sarcoma cell line 791T has been covalently coupled to purified human lymphoblastoid interferon alpha (IFN alpha). Conjugation does not interfere with antibody function, as the product binds to 791T cells and mediates complement-dependent tumour cell lysis to a degree equal to that of free antibody. The IFN activity, assessed by augmentation of natural killer (NK)-cell-mediated lysis, is reduced, but the conjugate does augment the killing of 791T and other tumour targets by peripheral blood NK cells. In admixture experiments the conjugate, when bound to unlabelled osteogenic sarcoma cells, also augments the killing of radiolabelled bystander cells. Neither free antibody nor the conjugate mediate antibody-dependent cellular cytotoxicity (ADCC), and augmented tumour cell lysis is a function of NK cell activation. This product provides for an alternative approach to cancer therapy via the activation of infiltrating hose effector cells using specifically targeted lymphokines.

Lymphoid infiltration and prognosis in colorectal carcinoma

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The human mixed lymphocyte-tumor cell interaction test. I. Positive autologous lymphocyte proliferative responses can be stimulated by tumor cells as well as by cells from normal tissues

Co-culture of cancer patients' nonadherent peripheral blood lymphocytes with irradiated autologous fresh tumor cells, termed the mixed lymphocyte-tumor interaction (MLTI) test, resulted in significant stimulation of 3H-Tdr in corporation on day 6 in 19 of 37 autologous combinations. The MLTI test was performed in a microtiter wells (0.2 ml) and a variety of solid tumor cells (sarcomas and carcinomas) were used. Tumor cells were dissociated from the fresh biopsy tissue by nontrypsin enzymatic digestion (deoxyribonuclease, hyaluronidase, and collagenase) and the tumor cells enriched by depletion of macrophages using adherence procedures. Occasionally, further tumor cell purification was achieved by separation of cells on the basis of size on dis-continuous gradients. Positive MLTI resulted in stimulation as high as 20-fold over the backgrounds of PBL and tumor cells cultured alone. Mean positive MLTI was SI of 7.7. The negative MLTI were not a reflection of generalized immunosuppression, because tumor cell preparations that did not stimulate autologous PBL did stimulate allogeneic PBL. In an additional patient, PBL not responding in the autologous MLTI did respond to allogeneic tumors. MLTI using cryopreserved cells reproduced the MLTI results using fresh cells in 11 of 16 tests; the other five tests were all positive in the fresh MLTI and negative when using cryopreserved cells. Despite reports from many other groups it appears that positive MLTI were not tumor-specific. In 14 experiments we were able to simultaneously test the proliferative response to autologous tumor as well as to an autologous normal tissue (lung, liver, colon, and bowel). In eight of these experiments positive responses were obtained with tumor stimulators and in seven of these, positive proliferation was also obtained with normal tissue.

Correlation between lymphocyte-mediated auto-tumor reactivities and clinical course. I. Evaluation of 46 patients with sarcoma

T-cell-enriched blood lymphocyte populations from 24 osteosarcoma and 22 soft-tissue sarcoma patients were assayed at the time of surgery for proliferative response to, and/or cytotoxic potential against autologous tumor cells. Tumor-free period and survival of the patients were correlated with the results obtained in the in vitro tests. The observation time was between 18 and 118 months (mean 62) for the osteosarcoma patients and between 18 and 72 (mean 42) for the patients with soft-tissue sarcoma. In both groups tumor-free period and survival were longer for those individuals who had auto-tumor reactivity. In the non-reactive group, all patients died within 3 years. Almost all patients had cytotoxicity against K562.

Correlation between lymphocyte-mediated auto-tumor reactivities and the clinical course. II. Evaluation of 69 patients with lung carcinoma

T-cell-enriched lymphocyte populations of 69 lung carcinoma (44 squamous cell, 23 adeno-, and two large cell carcinoma) patients were investigated at the time of surgery for proliferative response to, and/or cytotoxic potential against, freshly separated autologous tumor cells. Tumor-free period and survival time of the patients were correlated with the reactivity obtained in the in vitro tests. The observation time varied between 20 and 78 months (mean 52). Tumor-free period and survival time were longer and survival rate higher in the group with lymphocyte reactivity toward their tumors. In the non-reactive group, all patients but one died within 3 years. Almost all patients had cytotoxic lymphocytes against K562, the three who did not belonging to the category with short survival time.

Tumour-reactive lymphocytes stimulated in mixed lymphocyte and tumour culture. Clonal analysis of effector cells in cytotoxic and proliferative assays

Lymphocytes from cancer patients were stimulated in mixed culture with autologous tumour (MLTC) or pooled allogeneic lymphocytes (MLC). Both protocols induced increased uptake of 3H-thymidine at 5 days and the appearance of lymphoblasts. Blasts were isolated on discontinuous Percoll gradients and either expanded as bulk cultures or cloned directly under limiting dilution conditions in the presence of conditioned medium containing IL-2. Results with MLTC-blast-CTC have been reported elsewhere. MLC-activated cultures lysed autologous tumour but not autologous lymphoblasts. Lysis of some allogeneic tumours, lymphoblasts from members of the inducing pool, and K562 was also apparent. MLC activated cultures did not undergo restimulation in response to autologous tumour or lymphocytes but were restimulated by leukocytes from pool members. MLTC clones showed autologous tumour-specific cytotoxic activity or cross-reactive proliferative responses with tumours of the same site and histology. The majority of MLC clones cytotoxic for autologous tumour were also specific and did not lyse allogeneic tumour, K562, or lymphoblasts from the inducing pool. Two clones lysed autologous tumour and pool members. None of the clones tested proliferated in response to autologous tumour following MLC activation but some were responsive to pool members and one clone was restimulated by autologous monocytes. No association was found between clone phenotype and function. The implication of these data is that the effector cells with activity against autologous tumour induced in MLC arose largely by transstimulation of in vivo-activated tumour reactive lymphocytes by IL-2 release rather than expansion of NK-like effectors or sharing of antigenic specificities between tumour and allogeneic lymphocytes. Since MLC activation of cancer patients lymphocytes does not induce proliferative responses to autologous tumour it is unlikely to be a useful procedure in preparing cells for immunotherapy protocols.

Humoral and cellular immune reactions against tumor cells in patients with urinary bladder carcinoma. Correlation between direct and antibody-dependent cell-mediated cytotoxicity

Serum IgG fractions from a large and homogeneous group of patients with transitional cell carcinoma of the urinary bladder (TCC) were tested for their capacity to induce antibody-dependent cellular cytotoxicity (ADCC) with lymphocytes from healthy donors against a TCC-derived target cell and one derived from adenocarcinoma of the colon. Both targets have previously been shown to be of comparable susceptibility to cell-mediated lysis in vitro. Some of the IgG preparations showed strong and dose-dependent ADCC against either one or both targets, while others gave weak reactions or none at all. Similar results were obtained with IgG from a matched group of patients with prostatic carcinoma who were used as clinical controls (CC). In parallel experiments, lymphocytes taken from the two donor groups at the same time as the serum samples were tested for their direct cytotoxicity (CMC) against the two targets. CMC gave similar results to ADCC. The differences in cytotoxicity displayed by either IgG or lymphocytes from individual donors were analysed statistically, using nonparametric statistics. To avoid introducing bias due to arbitrary data selection, the entire set of results, comprising both high and low reactors, was included in the statistical assessment. ADCC of the TCC donors' IgG against the TCC target was significantly stronger than against the colon carcinoma and also significantly stronger than that of the control donors. Similarly, the TCC patients' lymphocytes displayed a significantly higher CMC against the TCC target than against the control targets. This was not seen when the lymphocytes from the patients with prostatic carcinoma were tested. When CMC and ADCC of individual donors were compared, a statistically significant correlation between these activities was seen in three of the four donor/target combinations. These results support earlier findings and suggest that a significant fraction of both the disease-related and the 'non-selective' CMC (NK) displayed by cancer patients lymphocytes against allogeneic tumor cells in vitro reflects antibody-dependent reactions.

Human spontaneous lymphocyte-mediated cytotoxicity (SLMC) against malignant and normal tissue-derived target cell lines tested in autologous and allogeneic combinations by the microcytotoxicity assay

Effector cell types and effector mechanisms of human spontaneous lymphocyte-mediated cytotoxicity (SLMC) were studied in a 44-h microcytotoxicity titration assay. Peripheral blood lymphocytes from cancer patients and controls were used as effector cells either unfractionated or after fractionation by rosetting techniques or affinity chromatography. The possible immunoglobulin dependency of the reactions was studied by incorporation of specific Fab fragments of rabbit anti-human IgG antibodies in the incubation mixtures. Twelve different target cell lines of either high or low sensitivity to SLMC and with or without easily detectable HLA antigens were used. Most of the target cells were cell lines derived from transitional cell carcinoma of the urinary bladder (TCC). Both allogeneic and autologous lymphocyte target cell combinations were tested. Although high- and low-sensitivity target cells differed significantly in susceptibility to lysis, the predominating SLMC was displayed by Fc-receptor-positive lymphocytes in both allogeneic and autologous combinations. Addition of the Fab anti-immunoglobulin reagent to the incubation mixtures resulted in strong inhibition of cytotoxicity regardless of the type of target cells used and in allogeneic as well as in autologous lymphocyte target cell mixtures. However, in some combinations no inhibition was seen and inhibition was usually not complete, suggesting that both immunoglobulin-dependent (i.e., ADCC-like) and immunoglobulin-independent mechanisms were involved in the cytotoxicity reactions. The results of the microcytotoxicity assay were compared with those obtained with aliquots of the same lymphocytes and target cells in an 18-h 51Cr-release assay. While similar results were obtained with high-sensitivity target cells, with low-sensitivity targets and in some autologous combinations the two assay systems registered lymphocyte/target cell interactions which differed with regard to specificity, effector cell type, and immunoglobulin dependency.

The biology of the human natural killer cell

Natural killer (NK) cells in the human are a population of large granular lymphocytes (LGL) with at least one unique surface antigen not expressed on cells of other lineages. NK-target-cell interaction appears to involve carbohydrate recognition and, following binding, the NK cells are induced to generate O2-, transmethylate membrane phospholipids, and activate phospholipase A2. Some or all of these activities trigger a cascade of events which ultimately leads to the secretion of a substance toxic to the target cell. A variety of genes controls various steps in this cytolytic pathway. There is a good deal of evidence in the mouse, and some in the human, that NK cells play a role in host surveillance against tumor development, resistance to viral infections, and, possibly, hematopoietic regulation.

Quantitation of proliferative and cytotoxic precursor cells directed against human tumours: limiting dilution analysis in peripheral blood and at the tumour site

Blood and tumour-infiltrating lymphocytes (TIL) from 16 cancer patients have been examined under limiting dilution conditions to determine the frequency of cells responding in mixed tumour-lymphocyte cultures (MLTC) to autologous tumour and Interleukin-2 (IL-2). Tumour-derived lymphocytes showed a high spontaneous response to IL-2 alone 1/1,900 in TIL; 1/6,000 in PBL suggesting the presence of "activated" T cells in situ. Proliferative frequencies were increased in MLTC in both blood (1/3,779) and TIL (1/1,084). Phenotypic analyses showed that total T-cell contents of the responder populations were comparable but TIL were enriched for the OKT8+ subset with a corresponding reduction in OKT4+. TIL showed increased numbers of OKMI+ and Tac+ lymphocytes. The major cytotoxic precursor expanding under these conditions was reactive against autologous tumour. K562 (NK) were present at a lesser frequency--particularly in TIL. The data show a concentration and activation of reactive lymphocytes at the tumour site and establish conditions for the clonal expansion of specifically cytotoxic T cells.

A trial of nonspecific immunotherapy using systemic C. parvum in treated patients with Dukes B and C colorectal cancer

In view of the relatively poor prognosis for patients after surgery for locally invasive colorectal cancer a trial of repeated systemic infusions of Corynebacterium parvum (CP) has been carried out. It is in this group of patients, with a high risk of recurrence from small residues of cancer left by the surgeon, that immunotherapy should have its optimum chance of success. A total of 92 patients were included in a randomized controlled study. The two groups were comparable in terms of tumour stage at presentation, operation performed and mean age of patients, but the control group had a preponderance of male patients. The study was carried out over 54 months. Treatment resulted in greater side effects than had been predicted, and as a result many patients could not be considered for inclusion.