IN-VIVO INTERLEUKIN-4 REGULATION OF ANTIBODY-RESPONSES IN EUTHYMIC AND ATHYMIC MICE TO A T-INDEPENDENT ANTIGEN (HYDROXYETHYL STARCH)

The aim of this work was to analyze the implication of IL-4 in the ant ibody response induced in vivo after immunization with a class II T-ce ll-independent (TI) antigen. IL-4 suppression, through administration of a rat monoclonal antibody antimurine IL-4 (11B11), in euthymic BALB /c mice during the course of immunization with the DNP-coupled hydroxy ethyl starch (TI antigen), inhibited the production of anti-DNP IgG1 a ntibodies, potentiated the synthesis of IgG2a and had no effect on oth er isotypes (IgM, IgG2b and IgG3). After IL-4 treatment of athymic BAL B/c mice in the same conditions, although the IgG2a production was not increased, the IgG1 synthesis was significantly decreased, as was obs erved in euthymice mice. These results demonstrate that cytokine IL-4 plays an active role in vivo in the regulation of antibody response af ter immunization by a T-cell-independent antigen, in normal as well as in nude mice. The origin of IL-4 in these animals and especially in t hose athymic mice remains to be determined.