Macrophage expression of interleukin-1 in lymphoepithelioid cell ("Lennert's") lymphoma.

Macrophage activation was studied in three cases of a genuine form of T cell non-Hodgkin's lymphoma particularly rich in epithelioid histiocytes, the so-called "lymphoepithelioid cell lymphoma" or "Lennert's lymphoma". Host tumor infiltrating macrophages actively produced Interleukin-1 as demonstrated by immunohistochemistry. The activated histiocytes also contained intracytoplasmic tumor cells which were either intact or at various stages of apoptosis. We postulate that in Lennert's lymphoma, tumor cells are capable of activating host macrophages. Initial macrophage activation is followed by IL-1 production with recruitment of additional macrophages accounting for the characteristic histological appearance of this tumor. The activated macrophages are also engaged in a phagocytic antitumoral response. Future studies should investigate if this host response can be potentiated.