Augmented natural killer activity in ovarian cancer patients treated with cimetidine

Cimetidine repurposed as a potential immunomodulatory agent against colorectal carcinoma: A systematic review

OBJECTIVE

To determine the survival benefit and immunomodulatory effects of cimetidine pre-, peri- or post-operatively in patients with colorectal cancer (CRC).

METHODS

A systematic review was conducted using PubMed and Cochrane Library to retrieve randomized control trials (RCTs) that investigated the effects of cimetidine on survival and immunomodulation via improvement in tumor infiltrating lymphocytes (TILs) and peripheral blood lymphocytes. The review was carried out in accordance with the extended Preferred Reporting Items for Systematic Reviews and Meta-analyses.

RESULTS

Four studies with the total of 267 patients were included in this systematic review. Treatment duration varied from 5 days to 1 year. Two studies reported a significant TIL response in the resected specimens after administering cimetidine, while one RCT showed an escalation of CD3, CD4 and CD57 lymphocytes in peripheral blood compared to the baseline following cimetidine treatment (p < 0.01). Of the three trials that examined the effects of cimetidine on survival, only two studies revealed significant survival benefit while the remaining study only showed a trend towards survival benefit.

CONCLUSION

Repurposing of existing drugs like cimetidine has a potential to offer a survival benefit by acting as an immunomodulatory agent in patients undergoing curative resection for CRC. However, the heterogeneity seen in current studies and the evolvement of adjunctive therapies for CRC warrant large-scale, well-designed prospective RCTs to establish the efficacy of cimetidine in CRC.

Enhancing the therapeutic efficacy of NK cells in the treatment of ovarian cancer (Review)

Ovarian cancer is a prevalent gynecological malignancy associated with a high mortality rate and a low 5‑year survival rate. Typically, >70% of patients present with an advanced stage of the disease, resulting in a high number of ovarian cancer‑associated deaths worldwide. Over the past decade, adoptive cellular immunotherapy has been investigated in clinical trials, and the results have led to the increased use in cancer treatment. Natural killer (NK) cells are cytotoxic lymphoid cells that recognize and lyse transformed cells, thereby impeding tumor growth. Thus, NK cells exhibit potential as a form of immunotherapy in the treatment of cancer. However, some patients with ovarian cancer treated with NK cells have experienced unsatisfactory outcomes. Therefore, further optimization of NK cells is required to increase the number of patients achieving long‑term remission. In the present review article, studies focusing on improving NK cell function were systematically summarized, and innovative strategies that augment the anticancer properties of NK cells were proposed.

Association between common genetic variant of HRH2 and gastric cancer risk

Histamine plays important physiological roles in the upper gastrointestinal tract and acts via the H2 receptor. The -1018 G>A (rs2067474) in an enhancer element of the promoter and non-synonymous rs79385261 (Asn46Thr) were identified in HRH2. We attempted to clarify the associations of these polymorphisms with gastric carcinogenesis. The study was performed in 321 patients with gastric cancer and 599 subjects with no evidence of gastric malignancies on upper gastroduodenal endoscopy. The genotypes were determined using a one-tube multiplex PCR-SSCP method. The degree of gastritis was assessed in 496 subjects and serum pepsinogen (PG) I/II levels were measured in 124 subjects without gastric cancer. The minor allele of Asn46Thr could not be detected. The frequencies of the -1018 A allele in the non-GC and GC groups were 13.5% and 8.26%, respectively (p=0.00077). Overall, -1018 GG homozygotes had an increased risk for developing gastric cancer (OR 1.68; 95% CI 1.17-2.42; p=0.0052), especially intestinal type cancer (OR 1.94; 95% CI 1.23-3.08; p=0.0047). In subjects aged >60 years, the adjusted risk for gastric cancer among individuals who were -1018 GG homozygotes was 1.87 (range 1.19-2.93; p=0.0065) compared with A carriers. In the gastric cancer cases located in the antrum and at comparative advanced stage, -1018 GG homozygosity was a significantly increased risk factor. In subjects >60 years, the metaplasia score was significantly higher in -1018 GG homozygotes than A carriers. Both atrophy and metaplasia scores were significantly increased with age only in -1018 GG homozygotes. The PG I/II ratio was significantly decreased in H. pylori positive GG homozygotes than negative GG homozygotes and positive A carriers. Our results suggest that -1018 GG homozygosity of HRH2 may be associated with the severity of gastric mucosal atrophy. This genotype has an increased risk for the subsequent development of gastric cancer, especially intestinal type, at advanced age.

Prospective, double-blind, placebo-controlled randomized trial of cimetidine in gastric cancer. British Stomach Cancer Group

Cimetidine is thought to inhibit suppressor T-lymphocyte function and preliminary evidence from a randomized trial indicated that it might prolong survival for patients with operable and inoperable gastric cancer. The British Stomach Cancer Group conducted a randomized, double-blind, placebo-controlled trial examining the effects of cimetidine (400 mg or 800 mg twice a day) on the survival of patients with early (stages I, II and III: n = 229) and advanced (stages IVa and IVb: n = 201) gastric cancer. The primary end point was death. A total of 442 patients were randomized by 59 consultants in 39 hospitals between February 1990 and March 1995. Log-rank survival analysis was used to assess differences between the groups. Three hundred and forty patients died during the study: 166 (49%) in the cimetidine treatment groups and 174 (51%) in the placebo groups. Median survival for patients receiving cimetidine was 13 months (95% confidence interval (CI) 9-16 months) and 11 months in the placebo arm (95% CI 9-14 months). There was no significant difference in survival between the two treatment groups (P = 0.42) or between different doses of cimetidine tablets (P = 0.46). Five-year survival of those patients randomized to cimetidine was 21% compared to 18% for those patients randomized to placebo. Cimetidine at a dose of 400 mg or 800 mg twice a day does not have a significant influence on the survival of patients with gastric cancer compared to placebo.

Cisplatin-based polychemotherapy reduces the natural cytotoxicity of peripheral blood mononuclear cells in patients with advanced ovarian carcinoma and their in vitro responsiveness to interleukin-12 incubation

BACKGROUND

The aim of the current study was to evaluate the in vitro effect of IL-12 on the natural cytotoxicity of peripheral blood mononuclear cells (PBMCs) obtained from patients who underwent adjuvant-based cisplatin polychemotherapy for advanced ovarian carcinoma. The authors also investigated amifostine, a cytoprotective agent that appears to protect against chemotherapy damage to healthy tissues, to determine its effects on natural immune function.

METHODS

Twenty-one women with advanced ovarian serous cystoadenocarcinoma who underwent adjuvant cisplatin-based polychemotherapy were included in the study, and 20 normal volunteer women matched for age served as controls. Six of the 21 women who underwent polychemotherapy received 1:3 amifostine pretreatment. Blood samples were obtained immediately before the first cycle of cisplatin-based polychemotherapy and within 24 hours after the completion of polychemotherapy infusion to evaluate the natural cytotoxic activity of PBMCs against the K562 cell line and the in vitro responsiveness of cytotoxic cells to interleukin-12 (IL-12).

RESULTS

The in vivo administration of cisplatin-based polychemotherapy significantly reduced the natural killer cytotoxicity of PBMCs toward undetectable levels (2.2+/-3.1 vs. 9.2+/-7.0 lytic units, respectively, after and before cisplatin; P < 0.01), and the in vitro exposure to IL-12 did not increase the cytolytic activity of PBMCs (1.9+/-2.1 lytic units). PBMCs from the 6 patients who received random amifostine pretreatment were shown to have retained natural killer cytotoxicity after in vivo administration of cisplatin polychemotherapy (9.7+/-6.7 vs. 9.6+/-6.0 lytic units, respectively, after and before cisplatin; P = 0.9), and the incubation with IL-12 increased cytotoxic activity (13.4+/-6.9 lytic units) toward the levels observed in PBMCs of controls (14.0+/-4.6 lytic units).

CONCLUSIONS

These data suggest that cisplatin-based polychemotherapy reduces the natural cytotoxicity of PBMCs in patients with advanced ovarian carcinoma as well as their in vitro responsiveness to IL-12 incubation. Amifostine demonstrated a protective effect on natural killer cell cytotoxicity and responsiveness to IL-12 in this small cohort of patients.

Comparison of immunomodulative effects of the histamine-2 receptor antagonists cimetidine, ranitidine, and famotidine on peripheral blood mononuclear cells in gastric cancer patients

BACKGROUND

Histamine-2 receptor antagonist (H2-RA) have been shown to improve the function of various parts of the immune system. The proposed mechanism of the immunomodulative effects of H2-RA has been considered to be the inhibition of suppressor T-lymphocyte activity, an increase in interleukin-2 production, and an enhancement of natural killer cell activity. Most of these studies were done with cimetidine. Comparative data with other H2-RA are limited and conflict on immunomodulative effects. Comparison of the actions of H2-RA on the immune system is required.

METHODS

We compared the immunodulative effect of the H2-RAs cimetidine, ranitidine, and famotidine on peripheral blood mononuclear cells (PBMC) in normal controls and patients with gastric cancer. DNA synthesis, cytotoxicity against K562 cells, and the levels of soluble interleukin-2 receptor (sIL-2R) in supernatant were measured after addition of the various H2-RA to PBMC cultures.

RESULTS

Subjects with gastric cancer showed significantly higher levels of suppressor lymphocyte activity than normal controls. These levels were restored to levels of normal controls by the addition of cimetidine. Statistically significant lymphoblastogenesis and cytotoxicity against K562 cells were observed only in cimetidine-treated PBMC (p < 0.05); such effects were not observed in ranitidine- or famotidine-treated PBMC. Significantly increased levels of sIL-2R were found in supernatants obtained from culture flasks treated with cimetidine and phytohemagglutinin or ranitidine and phytohemagglutinin (p < 0.01).

CONCLUSIONS

Of the three H2-RAs tested, cimetidine had the strongest and famotidine the weakest immunomodulating effect. Only cimetidine augmented the cytotoxicity and proliferative response of lymphocyte to mitogen; neither ranitidine nor famotidine had such an effect. These results might be due to their structural differences. In addition, the immunologic effects of H2-RA are unlikely to be mediated via specific interaction at the H2 receptor.

Cimetidine preserves non-specific immune function after colonic resection for cancer

Fifty consecutive patients undergoing resection of colorectal cancer were randomized to either receive cimetidine at a dose of 400 mg bd for a minimum of 5 pre-operative days, then intravenously for 2 postoperative days, or to act as controls. Baseline immune function was determined in all patients by in vitro testing of lymphocyte proliferation (LP) in response to mitogen, skin testing for cell mediated immunity (CMI) and measurement of lymphocyte subsets. Immune function was retested in both groups on the second postoperative day. In control patients the mean postoperative LP value was 41% of pre-operative levels (P < 0.0001) and the mean CMI reduced to 29% (P < 0.0001). Patients treated with cimetidine had no significant fall in these parameters. Numbers of T and natural killer (NK) cells fell after surgery in both groups, and B cell numbers were maintained in the cimetidine group. It is concluded that cimetidine reduces the immunosuppression that follows colonic resection.

Comparison of immunomodulative effects of histamine-2 receptor antagonists in gastric cancer patients: focus on the lymphoblastogenesis and cytotoxicity of peripheral blood mononuclear cells

A proposed mechanism of the immunomodulative effects of histamine-2 receptor antagonist (H2-RA) has been considered to be the inhibition of suppressor T-lymphocyte activity, an increase in interleukin-2 production of helper T-lymphocytes, and an enhancement of natural killer cell activity. Since there is a lack of comparative data about the immunomodulative effects of various H2-RAs, cimetidine, ranitidine and famotidine on peripheral blood mononuclear cells (PBMC), study of the comparison of the actions of H2-RA will be required. We compared the immunomodulative effect of each H2-RA on PBMC in patients with gastric cancer. DNA synthesis, cytotoxicity of PBMC against K562 cells and gastric cancer cell lines, and the levels of supernatant soluble interleukin-2 receptor (sIL-2R) were measured after the addition of each H2-RA, respectively. Increased suppressor cell activities were attenuated and restored to the levels of normal controls by the addition of cimetidine to H2-RA. Statistically significant lymphoblastogenesis and cytotoxicity against K562 cells were observed only in cimetidine-treated PBMC (P < 0.05). Such effects were not observed in ranitidine- or famotidine-treated PBMC. Neither cimetidine- nor ranitidine-activated activated PBMC showed any significant cytotoxicity against gastric cancer cells. Significantly increased levels of sIL-2R were found in supernatants obtained from culture flasks treated with cimetidine or ranitidine and phytohemagglutinin (P < 0.01). A significant correlation was found between the cytotoxicity of cimetidine- or ranitidine-treated PBMC and supernatant sIL-2R (P < 0.05). In conclusion, the most strongly modulative substance among H2-RAs was cimetidine and the least modulative drug was famotidine.(ABSTRACT TRUNCATED AT 250 WORDS)

Application of chemical immunomodulators to the treatment of cancer and AIDS

A number of potential advantages, development of promising new agents, and the discovery of synergy with cytokines or cell products continue to spur research into the application of chemical immunomodulators for the treatment of cancer and AIDS. In preclinical in vitro and in vivo systems, chemical immunomodulators definitely modulate the immune system and have therapeutic efficacy. Although clinical trials have shown the ability of these agents to modulate the human immune system, thus far chemical immunomodulators have generally not fulfilled the therapeutic promise generated in animal models for the treatment of human diseases. While the discrepancy in results between animal models and human trials is obvious, the basis is not apparent. Species differences in elimination kinetics, presentation of active drug at the site of action, and the development of tachyphylaxis have been postulated as reasons for the minimal activity of these agents in humans. In addition, the use of investigational techniques established for cytotoxic agents may not be appropriate for immunomodulators. As with any immunomodulator, determining an optimal immunostimulatory dose and schedule and applying the therapy to patients with minimal tumor burden would perhaps be more appropriate than use of a maximally tolerated dose in patients with advanced disease. A dose-immunological effect relationship has recently been demonstrated for levamisole at doses higher than those used for many years in levamisole trials (99). While research and clinical investigation have identified several potentially useful chemical immunomodulators, the elementary understanding of the biochemical mechanisms involved in immunoregulation remains basic. Future research must elucidate these mechanisms, particularly in humans, to maximize the benefits of chemical immunomodulators as single agents or combined with cytotoxic chemotherapeutic agents, surgery, radiation therapy, other immunomodulators, and antiviral agents.

Effect of histamine on the growth of human gastrointestinal tumours: reversal by cimetidine

The proliferative effects of histamine were examined on the human gastric tumour cell lines; MKN45, the gastrin producing subline, MKN45G, and the colorectal lines; LoVo and C170. The proliferation of MKN45 as assessed by 75[Se] selenomethionine uptake and cell counts was increased by histamine concentrations of 10(-7) and 10(-9) M. Histamine concentrations between 10(-6) and 10(-7) M maximally stimulated MKN45G proliferation which titrated out at lower histamine concentrations. The accumulation of cyclic adenosine 3',5' monophosphate (cAMP) in response to the same histamine concentrations was also increased in the two gastric cell lines. The histamine receptor antagonist, cimetidine (10(-5) M) reversed the histamine stimulated proliferation of both gastric cell lines despite having no effect on basal growth. The proliferation of the colorectal lines was unaffected by histamine. Histamine given locally at the subcutaneous implantation site of the tumour (1 mg/kg/day) increased the growth of MKN45G xenografts in nude mice. This was reversed by coadministration of cimetidine (100 mg/kg/day, given in the drinking water). Cimetidine also inhibited the basal proliferation of MKN45 xenografts. Histamine acting locally may enhance the proliferation of tumours arising within the stomach. Such effects may be blocked by administration of histamine receptor antagonists, such as cimetidine.

Effects of histamine type-2 receptor antagonists on indomethacin and IL-2 immunotherapy of metastasis

Histamine type-2 receptor antagonists (H-2RA) have been used chronically to prevent dyspepsia in cancer patients subjected to immunotherapy with chronic indomethacin (Indo) and intermittent IL-2 in our cancer centre. We tested the effects of these agents during immunotherapy of C3H/HeJ mice transplanted s.c. with 5 x 10(5) C3L5 mammary adenocarcinoma cells. Tumor-transplanted mice were divided into groups receiving: (1) Indo (14 micrograms/ml); (2) H-2RA, i.e. (a) ranitidine at 28.6 micrograms/ml (Ran-lo) or 143 micrograms/ml (Ran-hi), or (b) famotidine (Fam) at 4.3 micrograms/ml, or (c) cimetidine (Cim) at 107 micrograms/ml, all in the drinking water on days 5-24; (3) IL-2 (1.5 x 10(3) Cetus U i.p. every 8 h on days 10-14 and 20-24); (4) combinations of H-2RA + Indo; or (5) combinations of H-2RA + Indo + IL-2. Animals were killed on day 24 for examination of primary s.c. tumor growth, secondary lung metastasis and splenocyte cytotoxicity against YAC-1 lymphoma cells (51Cr release assay). Results revealed: (1) primary tumor growth was reduced in mice treated with Fam + Indo, Indo + IL-2 and any of the H-2RA + Indo + IL-2 (no difference observed within the last two groups); (2) lung metastases decreased in mice treated with IL-2 alone, Indo + IL-2, and Indo + IL-2 + Ran-hi; (3) splenic cytotoxicity was suppressed in tumor-bearing controls, with partial restoration seen in Ran (both doses), Ran-lo + Indo, Ran-lo + Indo + IL-2, and Cim + Indo + IL-2 treated groups. Nearly complete restoration was seen in Cim, Cim + Indo, Indo + IL-2, Ran-hi + Indo + IL-2, and Fam + Indo + IL-2 groups. Thus, addition of H-2RA did not alter the overall therapeutic efficacy of the standard Indo + IL-2 tumor immunotherapy.

The dorsal rat flap: a discussion of the model and the salutary effect of cimetidine on flap survival

Failure of skin flaps remains a significant clinical problem. The dorsal rat flap, a reliable experimental model, was used to test the efficacy of cimetidine in treating a failing flap. Flaps were elevated in 45 rats divided into three equal groups. Group 1 was a saline control group, Group 2 received cimetidine 250 mg/kg three times a day for 7 days postoperatively, and Group 3 received cimetidine for 1 day before surgery, and then as in Group 2. Necrosis was assessed on the seventh postoperative day. Group 2 had 31.1 +/- 1.3 (mean % +/- SEM) necrosis, significantly better than saline control animals (p less than 0.01) and pretreated animals (p less than 0.05). These results suggest the usefulness of cimetidine in ischemic flap surgery.

Changes of lymphocyte subsets in peripheral blood before and after operation of patients with advanced ovarian carcinoma

Comparison was made between lymphocyte subsets in peripheral blood from patients with benign ovarian tumor and those with advanced ovarian carcinoma. In addition, changes of lymphocyte subsets of patients with ovarian carcinoma before and after operation were also examined. The percentage and absolute number of CD3-/HLA-DR+ (B cells) in peripheral blood from patients with advanced ovarian carcinoma were significantly lower than values from patients with benign ovarian tumor, whereas both percentage and absolute number of CD3-/HLA-DR- (null cells) cells in patients with advanced ovarian carcinoma were significantly higher. Although there was no significant difference in natural killer (NK) cell subsets (CD57+ CD16- and CD57+ CD16+ cells) between patients with benign ovarian tumor and ovarian carcinoma, the percentage and absolute number of CD57-/CD16+ (highly differentiated NK cells) cells in patients with ovarian carcinoma were significantly higher than those in patients with benign ovarian tumor. Both the absolute number and percentage of CD3+/HLA-DR+ (activated T cells) cells in ovarian cancer patients with minimal residual tumors after operation were significantly increased, compared to the levels before operation, while the values in the patients with large residual tumors were significantly decreased. In addition, the percentage and absolute number of CD3-/HLA-DR- (null cells) cells in the patients with minimal residual tumors were significantly decreased after operation, while values in the patients with large residual tumors remained unchanged before and after operation. The patients with minimal residual tumors after operation were characterized by a significant increase in the percentage of CD57- CD16+ (highly differentiated NK cells) cells. On the other hand, in the patients with large residual tumors no change of the NK cell subsets was observed before and after operation.

Cimetidine: an immunomodulator

Suppressor T lymphocytes possess histamine2 (H2) receptors and contribute significantly to the function of the immune system. Experimentally, cimetidine, an H2-receptor antagonist, has been shown to enhance a variety of immunologic functions both in vivo and in vitro because of its inhibitory effects on suppressor-cell function. Successful tumor immunotherapy, as well as some protection from infection, has been reported in experimental animals. Patients receiving cimetidine have been shown to exhibit enhanced cell-mediated immunity as evaluated by increased response to skin-test antigens, restoration of sensitivity following development of acquired tolerance, and increased responses of lymphocytes to mitogen stimulation. Preliminary reports also indicate that cimetidine may offer therapeutic benefits for patients with Varicella zoster and Herpes simplex infections, as well as those suffering from mucocutaneous candidiasis and common variable hypogammaglobulinemia. These immunoregulatory effects are dose-related but are not always consistent. Because of its inhibitory effect on suppressor function, cimetidine treatment may be deleterious in patients with organ transplant and autoimmune disorders. Cimetidine should be used as an immunomodulator on an experimental basis only.

Adjuvant effects of prostaglandin D2 to cisplatin on human ovarian cancer cell growth in nude mice

Adjuvant effects of prostaglandin D2 to cisplatin on tumor growth were studied by using nude mice bearing HR cells derived from human ovarian carcinoma. Combinations of 0.2 or 0.4 microgram/ml cisplatin and 0.05 or 0.1 microgram/ml prostaglandin D2, which did not affect the HR cell proliferation alone, resulted in a significant inhibition of cell proliferation. In addition, tumor take of HR cells by nude mice in groups treated with a combination of cisplatin and prostaglandin D2 was inhibited. Although there was no significant difference between tumor volumes in mice treated with prostaglandin D2 alone or cisplatin alone and untreated mice, when cisplatin was administered with 1 mg/kg prostaglandin D2 the tumor volume was significantly smaller on days 21 and 35, compared to that of untreated mice. When cisplatin and 2 or 4 mg/kg prostaglandin D2 were combined, the tumor growth was significantly inhibited after day 21, compared not only to that of untreated mice but also of mice treated with cisplatin alone or prostaglandin D2 alone. Such a combination therapy by cisplatin and prostaglandin D2 seemed to result in prevention by prostaglandin D2 of immunological suppression which may be induced by cisplatin. Thus, such a combination therapy brought about a significant prolongation to the survival time.

Effect of cimetidine on survival after gastric cancer

The effect of cimetidine on survival was investigated in 181 patients with gastric cancer. Immediately after operation or the decision not to operate, the patients were randomised in double-blind fashion to placebo or cimetidine 400 mg twice daily for two years or until death, with review every three months. Median survival in the cimetidine group was 450 days (range 1-1826) and in the placebo group 316 days (1-1653). The relative survival rates (cimetidine/placebo) were 45%/28% at 1 year, 22%/13% at 2 years, 13%/7% at 3 years, 9%/3% at 4 years, and 2%/0% at 5 years. Survival in the cimetidine group was significantly longer than in the placebo group.

Effects of cimetidine on interleukin-2 production by peripheral blood lymphocytes in advanced ovarian carcinoma

The present study was designed to elucidate the effect of cimetidine on CD4 and CD8 positive cells, interleukin-2 (IL-2) production and IL-2 receptor expression in peripheral blood lymphocytes (PBL) from patients with advanced ovarian carcinoma during the course of combination chemotherapy. The absolute number of CD8 (but not CD4) positive cells in PBL from patients with advanced ovarian carcinoma before surgery was significantly higher than that with benign ovarian tumor, while the IL-2 productivity was significantly lower. However, the IL-2 receptor expression was comparable to that with benign ovarian tumor. When a combination chemotherapy consisting of cisplatin, adriamycin and cyclophosphamide was given to these ovarian cancer patients, the IL-2 production was markedly depressed. If cimetidine was given with the combination chemotherapy, the inhibition of IL-2 production by chemotherapy was significantly diminished with a significant increase of CD4 positive cells. On the other hand, the IL-2 receptor expression was not affected by this treatment. When treatment with cimetidine was initiated after completion of chemotherapy, the depressed IL-2 production was restored to the level of control patients with benign ovarian tumor. The restoration seemed to result from an increase in proportion of CD4 positive cells. However, the expression of IL-2 receptor remained unchanged even if cimetidine was given.

Interleukin 2 activity in peripheral blood mononuclear cells of patients with gynecologic malignancies

We studied production of, absorption of and response to interleukin 2 (IL-2) by peripheral blood mononuclear cells (PBMC) from 66 patients with gynecologic malignancies, in addition to measurement of the OKT 4/OKT 8 cell ratio. Patients with benign tumor served as controls. The OKT 4/OKT 8 cell ratio in patients with advanced (but not early) gynecologic malignancies was significantly lower than that in patients with benign tumor. PBMC from advanced cancer patients activated with phytohemagglutinin (PHA) had significantly lower IL-2 production compared to that from patients with benign tumors, while significant changes in their ability to respond to IL-2 and to absorb IL-2 were not observed. Absolute numbers of OKT 8 positive cells in PBMC of patients with good prognosis were significantly decreased after surgery and chemotherapy, while those of OKT 4 positive cells remained unchanged. Although IL-2 production in PBMC of patients with good prognosis was significantly elevated after chemotherapy, that in PBMC of patients with poor prognosis declined to about a half of pre-operative levels. The ability of PBMC to respond to IL-2 was significantly elevated not only in patients with good prognosis but also in patients with poor prognosis after termination of chemotherapy. On the other hand, the ability of PBMC to absorb IL-2 remained unchanged during the course of treatment. These findings may contribute to the understanding of tumor-induced immune suppression.