Immunological monitoring and immunotherapy in carcinoma of the lung

Skin reactivity to histamine and expression of histamine receptors mRNA in lymphocytes of healthy subjects and non-small-cell lung cancer patients before and after surgery

Histamine modulates an immunological response through stimulation of appropriate receptor--H1R proinflammatory or H2R suppressive. The participation of histamine in regulation of an immunological response in the course of neoplastic disease is determined by the expression of particular receptor. The aim of our work was the investigation of the expression of mRNA of two types of histamine receptors in peripheral blood lymphocytes and the evaluation of skin-prick test with histamine in lung cancer patients before and after surgery. The investigation was performed on 15 patients qualified to surgery before and 7-10 days after treatment and on 12 healthy subjects. Reverse transcriptase polymerase chain reaction (RT-PCR) with primers labeled with fluorescent dyes was performed. Intensity of fluorescence was expressed as relative fluorescence units (RFU). The data were analysed using ABI Prism 310 GeneScan collection software Version 3.1. Skin-prick test with histamine was evaluated after 10 min by measuring the diameter of the weal. The expression of H1R and H2R mRNA in healthy subjects was not significantly different in contrast to the lung cancer patients in which a significant prevalence of H2R mRNA expression was observed before surgery and only slightly decreased after (P < 0.001). Skin-prick test--negative in one patient before surgery, after treatment was positive in all patients and the diameter of histamine weal was significantly increased (P < 0.001). One may assume that the prevalence of the expression of H2R mRNA in patients reflects the status of immunosuppression caused by cancer. Since histamine exerts its suppressive activity trough H2R it seems reasonably to include the antagonists of this receptor to the cancer therapy which may restore a relative balance between accessibility of both types of histamine receptors.

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.

Comparison between bacillus Calmette-Guérin and the A60 mycobacterial antigen complex used as cancer-preventive immunotherapies

Preparations of liver or lysates of Mycobacterium bovis strain Calmette-Guérin (BCG) have long been used as treatments for a variety of cancer types, especially those involving the urinary tract, with varying success. This study was conducted to compare the antitumoral activity of BCG and the thermostable macromolecular antigen complex of BCG (A60) when used as preventive treatments, in conjunction with or without tumor antigens, against growth and dissemination of the EMT6 murine tumor cell line. It was demonstrated that tumor antigens alone did not significantly alter the oncological indexes, although a slight increase in both T lymphocyte and macrophage activations was found. It was further demonstrated that A60 induces a protective activity up to 40% greater than that of live BCG and that this protection was not accompanied by any of the adverse effects sometimes observed during BCG immunotherapy.

The effect of radiation therapy on immune function in patients with squamous cell lung carcinoma

The immune response is impaired in patients with malignancy, and radiation therapy (RT) can exacerbate the cancer induced-attenuation of immune response. In order to search for the fine mechanisms behind the RT-induced attenuation of cell-mediated immune response, we measured the number of lymphocytes in peripheral blood, its subsets, and lymphoblast transformation induced by phytohemagglutinin (PHA), purified protein derivatives (PPD), mitogenic monoclonal antibody anti-CD3, and mitogenic combination of anti-CD2 antibodies 9-1 and 9.6 before and after RT in 19 patients with squamous cell lung cancer. Radiation therapy significantly decreased the total numbers of lymphocytes, CD-3, CD-4, and CD8-positive lymphocytes in peripheral blood. However, RT did not change the percentages of lymphocytes and its subsets. Radiation therapy increased the percentage of interleukin 2 (IL-2) receptor-positive lymphocytes, and RT significantly decreased in vitro lymphoblast transformation by PHA, PPD, or monoclonal antibodies to T-cell surface antigens (anti-CD2 or anti-CD3). In vitro incubation with IL-2 did not increase lymphoblast transformation by anti-CD3 before RT but significantly increased after RT. In conclusion, we suggest that one of the fine mechanisms behind the RT-induced suppression of immune responsiveness of patients with lung cancer is a defect in IL-2 synthesis by lymphocytes.

Immune reactivity in bronchogenic carcinoma and its relation to 5-year survival rate

We performed a prospective study on the correlation of various parameters of the immune response with the 5-year survival rate in patients with bronchogenic carcinoma. Parameters were initially examined before starting treatment. Delayed hypersensitivity skin tests, lymphoblastogenesis, natural killer (NK) cell activity, and interleukin-2 (IL-2) production were employed to assess immune competence. Each reaction was classified into four or five grades in accordance with intensity; the 5-year survival rate of the patients showing each grade of the immune response was calculated. A correlation between response before treatment and the survival rate was most clearly noted for lymphoblastogenesis. The skin tests and the NK cell activity showed poorer correlations, and no exact correlation was noted between the IL-2 production and the immune response.

Different immune functions of peripheral blood, regional lymph node, and tumor infiltrating lymphocytes in lung cancer patients

Immune functions of peripheral blood (PBL), regional lymph node (RLNL), and tumor infiltrating lymphocytes (TIL) were evaluated in lung cancer patients. PBL had many natural killer (NK) cells and the highest NK activity, and it showed the highest augmentation of NK activity by interferon-gamma (IFN-gamma) + recombinant interleukin-2 (rIL-2) among the three groups of lymphocytes. PBL had high lymphokine-activated killer (LAK) activity of against a broad spectrum of cell lines and moderate activity against autologous tumor cells by increased effector to target (ET) ratio but the lowest ability of IL-2 production of the three groups of lymphocytes. The RLNL not associated with tumor metastasis had a few NK cells and lower NK activity than PBL, but its LAK activity was almost the same but not greater than that of PBL. RLNL had the highest ability of IL-2 production among the three groups of lymphocytes. All activities of RLNL associated with tumor metastasis were lower than those not associated with tumor metastasis. TIL exclusively consisted of T-cells, especially cytotoxic/suppressor T-lymphocytes. NK activity and lymphocyte blastogenesis of TIL were lower than those of other groups. The LAK activity of TIL differed greatly with the case, and it was the highest against autologous tumor cells among the three groups of lymphocytes in three of eight cases. These findings showed that PBL, RLNL, and TIL had characteristic subpopulations of lymphocytes and different functions of host immune responses in lung cancer. Efficient augmentation of the characteristic immune responses will lead to a more effective total cancer therapy.

Lymphocytopenia in high cancer risk population: evidence in automobile pattern makers

A total of 1454 automobile pattern makers were studied to determine the degree of lymphocyte reduction. These occupational workers have been known to be at high risk for colorectal cancer. As a group, pattern makers had significantly lower lymphocyte counts than the comparison group. The proportion of lymphocytopenia (less than 1500/mm3) in pattern makers was 26.2% as compared with 5.6% in the comparison group. Continuous monitoring of lymphocyte reduction in pattern makers may be worthwhile to evaluate whether these workers face a high risk for deficiency in lymphocytes in association with their risk for high rates of colorectal cancer.

Immunoincompetence in cancer patients. Assessment by in vitro stimulation tests and quantification of lymphocyte subpopulations

The authors performed a variety of lymphocyte-stimulation tests and quantified several lymphocyte subpopulations in 73 healthy controls and 72 patients with advanced cancer who were no longer receiving anticancer therapy. As a group, cancer patients had fewer lymphocytes and helper cells, but a greater proportion of suppressor cells and Ia+ cells than controls. The ratio of helper to suppressor cells was lower in the cancer group. Uptake of 125I-uridine was markedly depressed in cancer patients in the face of stimulation with various plant lectins, foreign lymphocytes, and varicella-zoster antigen. There was little correlation between any of the stimulation tests and any of the lymphocyte subpopulation proportions or numbers. The two tests that were most frequently abnormally low among the cancer patients were percent lymphocytes and number of helper cells (81% each). The most frequently abnormal functional assay in patients was pokeweed mitogen stimulation (59%). Three separate statistical methods selected the combination of percent lymphocytes, percent Ia+ cells, percent suppressor cells, number of helper cells, and pokeweed mitogen stimulation as being the best predictors of cancer/immunoincompetent status. This study confirms the breadth of immunoincompetence in advanced cancer patients as defined by in vitro techniques. A smaller battery of tests can be useful in monitoring the immune status of such patients, especially during therapy with proposed immune modulators.

Tumor specific reactivity during development of N-methyl-N-nitrosourea-induced rat colon cancer

Invasive colon adenocarcinomas with lymph node metastases can be induced in Sprague-Dawley rats by 15 weekly intrarectal injections of 2 mg N-methyl-N-nitrosourea (NMU). Extracts were prepared from invasive adenocarcinomas and normal rat colon mucosa by a 2 phase gradient. Mixed leukocyte tumor interaction (MLTI) assays stimulating lymphocytes from tumor-bearing and normal rats were performed using these extracts. Quadruplicate cultures were established with 2 X 10(5) lymphocytes and tumor or normal colon extract. Cultures were pulsed with H3 thymidine at 7 days and harvested 6 hours later. Results were expressed as net counts (experimental CPM minus background CPM). Reactivity in tumor-bearing animals was first seen when rat colons showed intraepithelial dysplasia histologically and was maximal when early invasive colon tumors were present. No difference in stimulation was seen between tumor-bearing and normal animal lymphocyte reactivity with normal colon extract. In conclusion, animals with NMU-induced rat colon cancer show specific tumor reactivity in MLTI assays. Immune reactivity in these animals may provide clues to clinical tumor status by immunologic assay.

Serial immune testing in surgically resected lung cancer patients

Immunoregulation of phytohemagglutinin (PHA) responsiveness by glass-adherent cells and prostaglandin-synthesizing cells was serially monitored in the peripheral blood mononuclear cells (PBMC) of surgically resected stage I and stage II lung cancer patients entered on a trial of adjuvant immunotherapy. The relationship between immunoregulatory cell function, immunocompetence, and disease relapse was determined. Immunoregulatory activity was measured in PHA-stimulated cultures in the presence and absence of 2 micrograms/ml indomethacin and in the presence and absence of glass-adherent cells. In each instance of disease relapse seen, an increase in immunoregulatory cell function to a level significantly different from normal was observed 3 months prior to or coincident with clinical confirmation of disease recurrence. This was usually associated with a decline in PHA responsiveness. In the patients who did not relapse, the levels of PHA responsiveness and immunoregulatory function persisted within normal limits throughout the course of study. Percentages and numbers of leukocytes and leukocyte subsets and delayed cutaneous hypersensitivity were also monitored in this study, but could not be consistently correlated with early changes in clinical disease status. These data suggest that the development of indomethacin-sensitive and glass-adherent suppressor cells may precede and predict for tumor recurrence in surgically resected lung cancer patients.

Immunologically defined prognostic subgroups as predictors of response to BCG immunotherapy

Fifty-two stage I and II patients with nonsmall cell lung cancer were randomized after resection to no further therapy, BCG, or BCG plus allogeneic tumor cells. Patients have been observed for 16-65 months (mean 39.5). When the two immunotherapy arms were combined and plotted against controls, trend analysis suggested (P = 0.088) an increase in disease-free interval (DFI) only for stage I patients. The one-way mixed lymphocyte culture (MLC) values were depressed in some patients prior to any immune stimulation. Immunotherapy significantly benefited DFI among patients with a depressed MLC.

A coded study of antitumor immunity to human lung cancer assayed by tube leukocyte adherence inhibition

The present study was undertaken to evaluate the specificity of antitumor immunity to human lung cancer, measured by an in vitro assay--tube leukocyte adherence inhibition (LAI). We standardized and monitored the putative tumor antigen activity of the extracts by testing leukocytes from controls and patients with lung cancer in the Montreal General Hospital. A specific antitumor response to a lung cancer antigen was detected with coded leukocytes from 56% (20 out of 36) of patients with epidermoid lung cancer. By contrast, 4% (2 out of 53) of patients with inflammatory lung disease and none of 46 other patients with cancer metastatic to the lung or with other diagnoses had an LAI-positive result. The LAI response was inversely related to the extent of cancer: 80% (8 of 10) with Stage I, 66% (2 of 3) with Stage II, 54% (6 of 11) with localized Stage III, and 33% (4 of 12) with widespread Stage III were LAI positive. Leukocytes from patients with epidermoid, adenocarcinoma, or small cell lung cancer reacted to a common tumor antigen shared by extracts of epidermoid and small cell lung cancer. This study with coded samples from a remote hospital confirms the results of other investigators that the LAI measures an antitumor immune response to human organ-specific neoantigens.

Specific and aspecific immune responsiveness in lung cancer patients: cutaneous delayed hypersensitivity reactions to a lung cancer-associated antigen

The ability of a lung cancer-associated antigen (LCAA) to provoke specific cutaneous delayed-hypersensitivity reactions has been studied on a group of 59 lung cancer patients. Biological activity of LCAA, monitored by skin testing, was demonstrated in 32% (17 of 53) of lung cancer patients, in 48.0% with limited disease, and in 17.2% with extensive disease. All the responders were in the group of normal reactors to standard recall antigens, if three antigens were used (PPDSK-SD, candida). No correlation was found between biological activity of LCAA and level of immunocompetence evaluated by lymphocyte-blastic transformation with PHA and count of rosette E-forming cells. These studies on the capacity to evoke specific DTH reactions in lung-cancer patients will be extended to the use of assays in vitro in the perspective of a more significant evaluation of immunocompetence levels.

Comparison of immune derangements in patients with different malignancies

Immune function was evaluated in 109 patients with carcinoma of the breast, bladder, head and neck, and lung. Patients with head and neck cancer showed the most profound derangements of immune function; patients with lung cancer showed no detectable abnormalities. Non-irradiated patients with disseminated head and neck cancer had significantly depressed lymphocyte counts (mean 1357/mm3, P less than .05), E-rosette forming cells (mean 770/mm3, P less than .05), and response to phytohemagglutinin (P less than .05) as compared to controls. This immunodeficiency was detected in patients with localized as well as advanced disease. Although significant differences were noted between patients with head and neck cancer and the other tumors, these differences were minimized by radiation therapy. All irradiated patients showed comparable degrees of immune dysfunction. Absolute Fc-receptor cells were depressed in all irradiated patients and in non-irradiated patients with disseminated breast cancer.

Estimation of PHA induced transformation in peripheral blood lymphocytes through measurement of their increased glycolysis. An enzymatic micromethod

Peripheral blood lymphocytes undergoing blast transformation after contact with PHA, show a rapid increase in glycolysis. The phenomenon can be quantitated by measuring the amount of lactate released in the culture medium. This measurement has been adapted to a micromethod which allows the study of PHA induced transformation in a large number of samples in a short time. The present method which avoids the use of radioisotopes correlates in 90% of the cases with the 3H-thymidine incorporation test.

Leukocyte migration inhibition assay in patients with bladder cancer

The leukocyte migration inhibition assay has demonstrated successfully tumor-associated antigenic activity in protein extracts of cell culture lines of a number of neoplasms. Our data have shown a high degree of leukocyte migration inhibition reactivity with protein extracts from the well characterized T-24 transitional carcinoma cell line. Thus, the leukocyte migration inhibition assay may prove a valuable method of in vitro assessment of the cell-mediated immunity of bladder cancer patients and as a method to monitor attempts at further purification of tumor-associated antigens.

Serum-mediated immunosuppression in lung cancer

Immunosuppression in 45 patients with lung cancer was studied by examining delayed cutaneous hypersensitivity reactions to DNCB and by analyzing the effect of the patient's serum on the proliferative response of normal donor lymphocytes. Both diminution of DNCB reactivity and inhibition of the proliferative response of normal donor lymphocytes to mitogens were associated with the stage of the disease and the presence of unresected tumor. Suppressive sera were associated with poor prognosis. The suppressive effects of patients' sera on lymphocytes from a normal donor suggest that the immunosuppression seen in lung cancer may be mediated by serum factors. The significant association of clinically evident tumor with this serum-mediated immunosuppression further suggests that the tumor itself could account for the appearance of these factors in the host. The clinical implications of these findings may be useful for designing new clinical trials.

Immunobiology of paediatric intracranial tumours. A preliminary report

Preliminary findings in the evaluation of the immune response of children with primary neoplasms of the CNS, mainly medulloblastomas, are reported and discussed. A broad scheme for the monitoring of B- and T-cell-dependent immunity and of delayed hypersensitivity reactions in this type of patient is presented. The most important immunobiological findings are discussed. Special attention is given to the striking failure of the T-cell-dependent pool (currently identified by "active" RFC and blastigenesis tests) and to the remarkable decrease of hypersensitivity reactions (depressed skin-test response), both of which seem to be related to the degree of malignancy of the tumour. A very peculiar feature, i.e., the appearance of cells with natural cytotoxic activity, is dealt with in some detail. Our present knowledge concerning the immunobiology of primary CNS neoplasms is still very incomplete, but seems to suggest a possible role for immunotherapy in paediatric neurosurgery.

Cell-mediated immunity in operable bronchial carcinoma: the effect of injecting irradiated autologous tumour cells and BCG

In 52 patients undergoing tests of cell-mediated immunity before surgical resection of bronchial carcinoma a positive tuberculin test result was found in 71% compared with 68% of age- and sex-matched controls. Sensitisation to DNCB occurred in 52% of 37 patients but in 78% of controls. There was depression of lymphocyte transformation by PPD in 19 patients compared with controls (P=0.001), but there was no difference in lymphocyte transformation by PHA or pokeweed mitogen between 34 patients and controls. In a pilot study patients were randomly allocated to autograft (eight) or non-autograft (seven) groups. The autograft group were given an intradermal injection of a suspension of irradiated autologous tumour-cells mixed with intradermal BCG on the day of operation. Tests of cell-mediated immunity were repeated two weeks after operation. Five patients in each group received a course of radiotherapy to the mediastinum three weeks after operation. There was a rise in cutaneous tuberculin reactivity (P=0.08) and total leucocyte count (P=0.09) in the autograft group postoperatively with a fall in total lymphocyte and T lymphocyte counts in the non-autograft group (P less 0.05). These differences, however, were not followed by any difference in the frequency of tumour recurrence or the survival rate two years after operation. The results show that the immunological surveillance mechanism is impaired even in patients with early bronchial carcinoma and that it is possible to overcome postoperative immunological depression with specific immunotherapy combined with BCG. This treatment did not produce any clinical advantage in this small number of patients and the skin lesions caused the patients considerable discomfort.

Cell-mediated immunity in patients with renal cell carcinoma as measured by leukocyte migration inhibition test

The cell-mediated immune (CMI) response to tumor-associated antigens present in 3 M KCL extracts of renal cell carcinoma tissue was measured in patients with renal cell carcinoma (RCC) by the leukocyte migration inhibition (LMI) test. Of 30 patients with histologically proved RCC, 19 (63%) gave a positive LMI test; whereas, 2 of 28 (7%) of the normal donors, 13 of 43 (30%) patients with other cancers, and 5 of 14 (36%) benign kidney disease patients gave positive tests. Thirteen per cent of RCC patients reacted to a normal kidney extract. Although 33% gave a positive response to a lung carcinoma extract, the incidence of reactivity was less than that observed with the lung cancer patients. These results suggest that a CMI response to a renal carcinoma-associated antigen was measured by the LMI test. Correlation of the LMI data with the stage of disease and clinical status indicated that 71% of patients that had a localized tumor and were clinically free of disease one year postnephrectomy lost their tumor-directed CMI response. Patients with distant metastasis (Stage D) were LMI positive provided they had not received radiation or hormone therapy at the time of testing. These results suggest that the demonstration of CMI, as measured by the leukocyte migration inhibition test, correlates with the presence of active disease.

Immunotherapy with BCG administered by scarification: standardization of reactions and management of side effects

The method of administering BCG by scarification is described in detail. A system of classifying the intensity of local reactions is proposed to standardize administration. The experience of the M.D. Anderson Hospital involving over 2700 patients is reviewed. Administration of BCG by scarification has been accomplished with safety and has been well tolerated and accepted. The most commonly observed side effects are discussed as well as their management.

Improvement of in vitro mitogen proliferative responses in non-Hodgkin's lymphoma patients exposed to fractionated total body irradiation

Patients with non-Hodgkin's lymphomas who failed to respond to chemotherapy were treated with low dose fractionated total body irradiation (TBI). Prior to during and after scheduled therapy, their clinical status was evaluated and peripheral blood studies were performed to enumerate EAC and E rosetting cells and to measure proliferative responses to mitogens. Peripheral blood abnormalities were present prior to TBI using these in vitro assays. Patients who obtained clinical remissions following therapy had restoration of mitogen progressive disease had no change in their ability to proliferate in response to mitogens. Normalization of EAC and E rosetting profiles often occurred regardless of clinical response. These data indicate that low dose fractionated TBI produces clinical and in vitro detectable immunological changes. Furthermore, they show that improvement in mitogen responsiveness correlates best with good clinical responses.

Overview on new immunologic markers for diagnosis of cancer

There is a large and increasing number of tumor-associated markers which can be detected immunologically and which may be useful for detection, diagnosis and monitoring of cancer. These include cell surface antigens and other components specifically associated with tumor cells, ectopic hormones, and normal materials which are produced in increased amounts by or in response to the tumors. Some of these markers are only antigenic in heterologous species, whereas others are reacted to by the tumor-bearing host. The major current problem is to determine which of these markers may be applied to practical problems of immunodiagnosis.

Immunologic detection of acoustic neuroma: preliminary report

In an attempto to provide preoperative histologic identification of internal auditory canal and cerebellopontine angle tumors, and to attempt to detect small tumors and recurrent tumors, immunologic aspects of acoustic neuroma patients and control subjects were studied. Reactions based upon the interaction of patients' fresh lymphocytes in contact with acoustic neuroma antigens were studied by a leukocyte migration inhibition (LMI) assay and a locally developed refinement, the plasma effect assay. These were performed either preoperatively, postoperative, or both, in 17 patients with surgically confirmed acoustic neuromas and in 24 controls subjects. Preoperative tumor patients had a higher likelihood of having elevated LMI and plasma effect assay values than normals. False positive results were rare and the combination of the LMI and plasma effect assay decreased false negative responses to 20%. Meaningful conclusions must await more extensive testing but it has been demonstrated that tumor associated antigens do exist on the membranes of schwannoma cells and that most patients with an acoustic neuroma mount a cell-mediated immune response against these antigens.

Relationship of cell-mediated cytotoxicity against melanoma cells to prognosis in melanoma patients

The cell-mediated cytotoxicity (CMC) of blood mononuclear cells against cultured human melanoma cells was measured in patients after surgical removal of localized melanoma, at a time when they were considered on clinical grounds to be free of melanoma. It was found that the distribution of CMC values against melanoma cells in melanoma patients was different from that in control subjects, and several sub-populations of melanoma patients were evident on the basis of these measurements. No difference in distribution of CMC values was found against non-melanoma cells, which suggested the changes were specific for melanoma. The proportion of patients with recurrence of melanoma was compared between the patient groups with low, normal or high CMC values against cultured melanoma cells after surgery. Analysis for periods extending to 2 years showed that patients with low CMC values after surgery had a significantly higher incidence of recurrence from melanoma than patients with normal or high CMC values. These results suggest there may be a sub-group of melanoma patients who have intrinsically low CMC against melanoma cells, and that this may be an important predisposing factor in the development of recurrent melanoma.

The relative proliferation index as a more sensitive parameter for evaluating lymphoproliferative responses of cancer patients to mitogens and alloantigens

Lymphocyte proliferation (LP) assays were performed in microculture using the T-cell mitogens phytohemagglutinin (PHA) and concanavalin A (Con A); the T + B cell mitogens, pokeweed mitogen (PWM) and staphylococcal phage lysate (SPL); and a pool of allogeneic stimulating leukocytes in one-way mixed leukocyte cultures (MLC) in lung and breast cancer patients and normal individuals. The resultant data were expressed in three different ways: (1) as mean counts per minute (CPM) of tritiated thymidine incorporation; (2) as a stimulation index (SI) and (3) as a relative proliferation index (RPI). The RPI is defined as the ratio of net CPM (nCPM) in experimental cultures with stimulant (E) minus medium control cultures (C) of a test individual to the mean nCPM of three or more normal individuals examined in the same assay on the same day. These expressions were then compared for their ability to discriminate between LP responses in cancer patients and normal individuals. The RPI value and selected cut-off values gave the most sensitive measure for the determination of depressed proliferative responses. These analyses demonstrated that lung carcinoma patients were depressed to PHA (50%), MLC (47%), PWM (43%) and Con A (40%). To a lesser degree, breast carcinoma patients were also depressed to MLC (36%), PHA (31%), PWM (27%) and Con A (19%). Our data indicate that the use of the RPI in the analysis of LP response represents an improved method for detecting impaired response of lymphocytes to general mitogens and alloantigens which can consistently reveal immunosuppression in many cancer patients and may be useful for serial monitoring of individual patients.