A long-term 51chromium assay for in vitro cell-mediated tumor immunity. Correlation with simultaneously performed microplate assays

In vivo and in vitro effects of xenogeneic immune ribonucleic acid in patients with advanced renal cell carcinoma: a phase I study

Based upon demonstration in our laboratory of repeated prevention of pulmonary metastases by adjuvant immune ribonucleic acid in animal preparations, xenogeneic immune ribonucleic acid was given in a phase I study to patients with advanced renal cell carcinoma. Six patients were treated with intravenous infusions of autologous lymphocytes incubated in vitro with immune ribonucleic acid extracted from splenocytes of guinea pigs immunized with the patient's own tumor. Serial peripheral blood lymphocytes were obtained during and after each treatment with immune ribonucleic acid for in vitro evaluation of cell-mediated cytolysis by 51chromium release assay and 125iodine iododeoxyuridine assay against allogeneic renal cell carcinoma targets and melanoma targets. Neither toxicity nor enhancement of tumor growth was observed. All patients demonstrated significantly increased cell-mediated cytolysis against allogeneic renal cell carcinoma targets but no change against melanoma targets. Increased cell-mediated cytolysis could be demonstrated in individual blood samples after incubation with immune ribonucleic acid. Further, progressive in vivo effect was demonstrated in in vitro assay of serial peripheral blood lymphocytes before each successive exposure to immune ribonucleic acid. Increased cell-mediated cytolysis persisted in peripheral blood lymphocytes up to 9 months after therapy. Although without controls 1 patient had complete response and 2 patients had partial responses (8 to 18 months). Two patients had stabilization of the disease for 3 to 4 months and 1 patient had progression of cerebral metastases. One patient is alive 24 months after therapy. These results would favor the institution of a randomized prospective trial in patients with advanced renal cell carcinoma or lesser tumor burdens.

Electrolysis and surgery in experimental tumours in the rat

An experimental tumor (DMH W49) was inoculated subcutaneously in rats and treated by either electrolysis or surgery. The efficiency of these treatments was approximately the same. There was no evidence that electrolytic treatment led to the production of humoral antibodies against the tumour.

Susceptibility of adherent versus suspension target cells derived from adherent tissue culture lines to cell-mediated cytotoxicity in rapid 51Cr-release assays

Preparation of target cells from tissue culture lines which grow adherent to tissue culture vessels is often desirable for tests of cell-mediated cytotoxicity (CMC). In the present study we used cells derived from adherent tissue culture lines to compare the merits of suspension vs. adherent target cells in short-term 51Cr-release assays. Cytotoxic activity of murine spleen cells sensitized in vitro against allogeneic spleen cells or syngeneic sarcoma cells was tested with fibroblast or sarcoma target cells. In parallel tests, aliquots of tissue culture lines were detached and used as either suspension or adherent target cells in CMC assays, matching the concentrations of suspension and adherent target cells. In both allogeneic and syngeneic combinations adherent target cells released less 51Cr spontaneously and were more susceptible to CMC than their suspension counterparts.

Spontaneous 51Cr release by isolated rat hepatocytes: an indicator of membrane damage

Radiochromium uptake and release by isolated rat hepatocytes in suspension was monitored under continuous-labeling conditions. Cell protein remained unchanged during the absorption phase, whereas the release of 51Cr correlated well with the loss of cell viability and release of cytoplasmic protein. The results suggest that under equilibrium conditions, 51Cr release represents an efflux of label from damaged or dying preparations and not an elution of radioisotope from intact cells.

An isotope-release assay and terminal-labeling assay for measuring cell-mediated allograft and tumor immunity to small numbers of adherent target cells

A 51Cr-release assay and terminal 51Cr-labeling assay for measuring cell-mediated immunity to adherent target cells is described. Both techniques utilize small 10 microliter-per well microtiter plates, require low numbers of target cells (50-500 per well), and consequently, relatively small numbers of effector cells per well (3x10(3) -1x10(5)). Both assays are objective, quantitative, and simple to perform. The suitability of these techniques for monitoring immunologically specific, cellmediated, cytotoxic response to syngeneic and allogeneic tumor cells and normal skin fibroblasts is demonstrated. Lymph node cells, spleen cells and peritoneal exudate cells serve as effectors.

Effects of presensitization in vivo on cell-mediated responses to embryonic antigens in vitro

Lymphoid cells specifically reactive with antigens shared by rat bowel carcinomas and mid-term embryo cells were generated by in vitro culture on monolayers of embryo cells. Spleen cells from WF females were cultured for 5 days on monolayers of syngeneic embryo cells or adult cells and assayed for cytotoxic activity on syngeneic embryo, bowel carcinoma, or adult fibroblast target cells in microcytotoxicity and 51Cr-release assays. After culture on embryo monolayers, spleen cells were cytotoxic for embryo and tumor but not for adult fibroblast target cells. Enhanced cytotoxicity was recorded when the spleen cells were cultured from females after interstrain (WF X BN) pregnancy rather than from virgin females. In contrast, previous intrastrain (WF X WF) pregnancy appeared to depress the generation of spleen cells cytotoxic for target cells bearing embryonic antigens.

In vitro cell-mediated immune reactions of melanoma and colorectal carcinoma patients demonstrated by long-term 51chromium assays

In a series of consecutive 51chromium (51Cr) assays, 21 melanoma and 14 colo-rectal carcinoma patients were tested for their in vitro cell-mediated immune reactions to melanoma, rectal adenocarcinoma, and normal fibroblast target cells. Blood lymphocytes (BL) from four individuals were included in each experiment. In 9/14 experiments the BL effects of 2 melanoma patients were compared to BL effects of 2 colorectal carcinoma patients. In two experiments, BL from 1 melanoma patient and 1 colorectal carcinoma patient were compared for cytotoxic effect with each other and with BL from 2 normal healthy donors, and in the remaining 3 experiments BL from 2 melanoma patients were compared with BL from 1 healthy donor and one patient bearing a tumor which was neither a melanoma nor a colorectal carcinoma. Eleven out of 14 experiments were performed in a criss-cross manner. Target cells in the first three tests of this series consisted of tumor cells and fibroblasts explanted from a single melanoma patient. In all of the remaining experiments, each BL population was tested for cytotoxicity against both a tumor-fibroblast target cell pair explanted from one of two melanoma patients and a tumor-fibroblast target cell pair explanted from a rectal adenocarcinoma patient. Out of 35 tumor patients, 27 (77%) demonstrated a selective cytotoxic effect on the tumor target cells compared to the corresponding fibroblasts, while 4 patients (11%) showed a selective effect on the fibroblasts, and 6/29 patients showed a selective effect on the other type of tumor cells compared to matching fibroblasts. In 8/11 experiments (including two repeat tests) tumor-specific BL effects were demonstrated in a criss-cross manner. BL separations and 51Cr tests were repeated in 11 of the 35 patients 2-4 weeks after their original tests. BL populations from these 11 patients reproduced their individual earlier effects, whether these effects showed specific, non-specific, or no cytotoxicity. In each assay, differences in sensitivity between fibroblasts and tumor target cells in matched pairs were analyzed by comparing the effects of BL from the two controls. No differences in target-cell sensitivity could be demonstrated.