Recombinant IL-4 and IFN-γ activate locomotor capacity in human B lymphocytes

Recombinant human interleukin-4 (IL-4) or interferon-gamma (IFN-gamma) were added to cultures of B-enriched human lymphocytes from normal blood, or to the lymphocytes from five patients with chronic lymphocytic leukaemia (CLL). IL-4 and IFN-gamma caused the B lymphocytes to acquire locomotor capacity, as judged by morphological polarization and invasion of collagen gels. This was detectable in normal B cells within a few hours of culture and fully developed by 24-48 hr. It was inhibited by the presence of cyclosporin A. The responding, motile cells also increased in size. These findings suggest that B lymphocytes acquire locomotor capacity early in growth, as the cells move from G0 to G1. IL-4 or IFN-gamma had no direct effect in polarizing lymphocytes in a short-term (30-min) assay, thus they do not behave like chemotactic factors. They slowly increase the proportion of locomotor cells in B-lymphocyte populations, and these motile cells respond by polarization to factors released by the growing cells into the medium.