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

Abstract

In vitro assays of cell-mediated tumor immunity utilizing 51Chromium (51Cr) labelling of cultured adherent solid tumor cells were designed which allowed an effector cell/target cell incubation time of 48 h without overriding spontaneous 51Cr release. In a series of 16 consecutive experiments, blood lymphocytes from healthy human donors, from patients with tumors unrelated to the cultural tumor target cells, and from colon carcinoma and melanoma patients were tested for their cytotoxic effects on various target cell pairs, human colon carcinoma, melanoma, or skin fibroblasts. The same reagents were used in simultaneously performed microplate and 51Cr assays. Results obtained by visual counting of microplate tests and by 24-h assays of 51Cr release or 51Cr retention correlated in 20/25 effector-cell/target-cell combinations. In a series of six consecutive experiments, lymph-node cells from untreated Wistar/Furth rats, and rats bearing either chemically-induced colon carcinoma NG-W1 or polyoma virus-induced sarcoma P-W13 were tested for their cytotoxicity on syngeneic rat colon carcinoma and sarcoma target cells. Criss-cross type experiments were performed by microplate and 15Cr techniques done in parallel. Results obtained by visual counting of microplate tests and by 48 h assays of 51Cr release or 51Cr retention correlated in 15/18 effector-cell/target-cell combinations.