Demonstration of specific cell‐mediated anti‐tumor immunity in lung cancer to autologous tissue extracts

Cell‐mediated immunity (CMI) of lung cancer patients to autologous tumor antigens was assessed by mixed lymphocyte tumor interactions (MLTI) as measured in a microculture (200 μl) lymphocyte proliferation (LP) assay. Positive lymphoproliferative responses were observed with cryopreserved intact mitomycin‐C‐treated autologous tumor cells (8/12 or 67% patients reactive) and with hypotonic membrane extracts (HMP) of tumor cells (28/40 or 70%). Good correlation was found between reactivity to tumor cells and extracts in parallel testing. In contrast, HMP of autologous normal lung tissue elicited very little LP reactivity, with only one patient giving a weak response by the SI criterion and low level of n cpm. Upon repeat testing, many patients gave reproducibly positive LP responses to tumor HMP. Patients at all clinical stages of disease and with different histologic tumor types had a similar proportion of HMP reactivity. Most reactive patients responded to a broad range of protein concentrations of tumor HMP, and LP responses were frequently elicited with 1 μg or less of HMP. Thus, HMP appear to afford a convenient source of reactive tumor antigen for assessing anti‐tumor immunity.