Immunological activities of RU-41740, a glycoproteic extract from klebsiella pneumoniae: I.— Activation of murine b cells and induction of interleukin-1 production by macrophages

Abstract

RU-41740, a glycoprotein extract from Klebsiella pneumoniae K2O1 strain, is an immunomodulating compound which has been shown to reduce infectious episodes in immunodeficient patients. Data from preliminary experimental designs suggested that RU-41740 could affect several target cells, such as T cells, B cells and macrophages. In the present report, we show that RU-41740 is a selective B-lymphocyte activator. It induces blast transformation in Nude mouse spleen cell cultures and in B-cell-enriched fractions obtained from normal mice. It does not activate T lymphocytes to proliferate. Activation of mouse B lymphocytes by RU-41740 is not affected by removal of adherent cells. RU-41740 also activates immunoglobulin secretion by murine B lymphocytes. Incubating spleen cells from C3H/HeJ mice with RU-41740 results in cell proliferation and activation of antibody-forming cells. This suggests that B-cell activation is not due to LPS contamination. Other experiments show that RU-41740 can also trigger mouse macrophages to produce interleukin-1 activity. Indeed, supernatants from peritoneal adherent cells incubated in the presence of RU-41740 can stimulate blastogenesis in thymocytes from C3H/HeJ mice. Thus, B-cell activation and IL-1 production by macrophages could constitute two additive mechanisms involved in immunomodulation induced by RU-41740.