Expression of interleukin-1 receptor antagonist protein in malignant lymphomas. An immunohistochemical study.

Objective: Interleukin-1 (IL-1) receptor antagonist (IL-1ra) is a naturally occurring modulator of IL-1 that functions by competitively binding to IL-1 receptors without producing biologic effects. Interleukin-1 is believed to be a mediator involved in production of constitutional symptoms in patients with malignant lymphoma. Because we know of no study regarding IL-1ra expression in lymphomas, we tried to demonstrate the presence of IL-1ra in lymphomas using immunohistochemistry.

Design: Anti-IL-1ra monoclonal antibody was applied to paraffin sections of Hodgkin's disease and non-Hodgkin's lymphoma (NHL) with avidin-biotin complex method.

Results: Interleukin-1 receptor antagonist was found to be present primarily in benign reactive histiocytes in neoplastic tissue. Positivity for IL-1ra was found in 12 (67%) of 18 cases of Hodgkin's disease and 53 (29%) of 184 cases of NHL. The positivity rate varied in different subtypes of NHL. Three percent (1 in 30) of follicular small cleaved-cell lymphomas contained IL-1ra-expressing histiocytes, whereas 52% (17 of 33) of diffuse mixed-cell and 27% (12 of 44) of diffuse large-cell lymphomas contained IL-1ra-positive histiocytes. Nine of 13 (69%) cases of high-grade NHLs contained IL-1ra-expressing histiocytes. Among cases of NHL, the higher-grade NHL cases showed higher percentages of positivity.

Conclusions: The findings further support the hypothesis that IL-1 may play a role in producing constitutional symptoms.