[Immunohistochemical in situ demonstration of cytokines in Hodgkin and non-Hodgkin lymphoma].

Primary biopsies from 149 patients with malignant lymphomas were examined by histological and immunohistochemical techniques. Twenty eight cases were classified as Hodgkin's disease and 121 as non-Hodgkin's lymphomas. The immunohistochemical distribution of cytokine expression (Il-1 alpha, Il-1 beta, Il-6 and TNF-alpha) was demonstrated in neoplastic cells and in tumor-associated macrophages (TAM). Neoplastic cells showed mostly weak positivity for TNF-alpha in 40% of Hodgkin's disease and in 20% of T cell lymphoma cases. Two groups of malignant lymphomas were established which differed in the numbers of cytokine expressing TAM. The first group consisted of malignant lymphomas which contained large quantities of cytokine-possessing TAM. In the second group significantly lower frequencies of cytokine expressing TAM were found. In both groups high and low grade malignant lymphomas were encountered. There was a significantly positive correlation between the number of Il-6 possessing TAM and the proliferation of lymphoma cells in only the non-Hodgkin's lymphomas. Our results suggest a paracrine tumor growth stimulating mechanism which is created by a self perpetuating cytokine production loop. A supposed cytokine produced by neoplastic cells dependent from their proliferative activity may induce Il-6 secretion by TAM. Il-6 in turn may stimulate the proliferation of the lymphoma cells without maturation thus leading to a self-sustaining growth.