[T-lymphocyte induced normalization of transformed malignant fibroblasts: lymphokine with normalization factor...

Normalizing influence of different lymphocyte populations and their soluble factors on L-929 transformed malignant fibroblasts (L cells) has been examined. It was demonstrated that splenic T-lymphocytes caused stable (heritable) normalization of receptor apparatus, biophysical and proliferative characteristics of L cells. Lymphokine with the activity of normalization factor (NF) was purified from 24-hour immunocyte conditioned medium. Stability of the normalization phenomenon was caused by NF induced synthesis of functionally analogous factor in L cells. The results obtained indicate the existence of non-cytotoxic mechanisms of tumour growth immunological control. The isolated lymphokine possessed also the activity of early embryonal cell differentiation factor. It is suggested that lymphokines with the activity of NF are physiological regulators of nonlymphoid cell differentiation.