BCL-2 IMMUNOREACTIVITY IN SALIVARY-GLAND NEOPLASMS IS UNRELATED TO THE EXPRESSION OF MESSENGER-RNA FOR NATURAL-KILLER-CELL STIMULATORY CYTOKINES INTERLEUKIN (IL)-2 AND IL-12

Certain cytokines are involved in the generation of natural killer (NK ) cells and participate in the regulation of the proto-oncogene bcl-2. We aimed to study the mRNA expression of interleukin (IL) -2, IL-4 an d IL-5, the composition of the tumour infiltrating lymphocytes (TIL), and the expression of bcl-2 in 14 benign and malignant human parotid t umours, T IL were predominantly composed of T lymphocytes and NK cells . We found evidence for the homing of T cells, and for generation of N K cells in the vicinity of the tumours. mRNA for IL-2 and IL-12, were identified but IL-4 mRNA was not found. The cytokine profiles and the composition of TIL of the two tumour categories were indistinguishable , suggesting that these host-response variables do not explain the dif ferences in biological behaviour of these particular tumours. The resu lts support a shift towards Th1 (T helper 1) cells and interferon-gamm a production, and that IL-12 also in vivo may play an important role i n the regulatory interaction between innate resistance and adaptive im munity in tumour diseases, Most infiltrating lymphocytes showed strong expression of bcl-2; an interesting observation with regard to lympho cytic apoptosis in neoplastic diseases. The immunoreactivity fot the b cl-2 protein varied considerably between and within tumours, and almos t all benign tumours showed strong bcl-2 positively whereas several of the malignant tumours showed weak or absent staining. The variable ex pression of bcl-2 protein suggests a different susceptibility of tumou r cells to apoptosis. The results also indicate that bcl-2 cannot play a major role as protective agent in the specific apoptotic path way i nduced by NK cells.