Interleukin 4 induces cellular adhesion among B lymphocytes.

We here report that interleukin 4 (IL-4) alone is able to induce cellular adhesion among mouse lymphocytes, and together with lipopolysaccharide (LPS), it increases the adhesion induced by LPS. The adhesion was inhibited by antibodies against IL-4. IL-4 appears to be acting mainly on B lymphocytes, since the response caused by IL-4 alone was much less sensitive to depletion of adherent cells than the LPS response. Depletion of T cells had no effect on IL-4- or LPS-induced adhesion. IL-4 could together with Con A, but not alone, induce adhesion among T cells. Cell clusters, which were formed after 2-3 days of LPS plus IL-4 stimulation, could be completely dissociated, and when the cells were recultured in medium, they readily started to reaggregate. The adhesion molecule lymphocyte function-associated antigen 1 (LFA-1) is, at least in part, involved in LPS plus IL-4-induced adhesion. Antibodies against LFA-1 inhibited the adhesion, but antibodies against other cell surface molecules were without inhibitory effect. Adhesion induced by IL-4 alone may involve other adhesion molecules than LFA-1.