[Activation of murine B lymphocytes by RU 41740, a glycoprotein extract from Klebsiella pneumoniae].

RU 41740, a glycoprotein extract from K. pneumoniae K2O1 strain, is an immune modulating compound which has been shown to reduce infectious episodes in deficient patients. Data from experimental designs suggest that RU 41740 could affect several target cells, such as T cells, B cells or macrophages. In the present report we show that RU 41740 is a selective B cell activator. It induces blast transformation in normal and nude mouse spleen cells and does not activate mouse T lymphocytes to proliferate. Activation of mouse spleen cells 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.