Antigen-Independent Regulation of Cytoplasmic Calcium in B Cells with a 12-kDa B-Cell Growth and Anti-CD19

摘要

Increases in cytoplasmic free calcium (Ca(2+))i) can be induced in resting B cells either by a low molecular weight (12-kDa) B-cell growth factor (LMW-BCGF) or by crosslinking the B-cell antigen CD19 with monoclonal antibody (mAb). LMW-BCGF causes a slow (Ca(2+))i increase in peripheral blood and tonsillar B cells but has no effect on (Ca(2+))i in resting T cells. B-cell (Ca(2+))i responses mediated by anti-surface immunoglobulin (sIg) or anti-CD19 do not show additive (Ca(2+))i responses. LMW-BCGF- and anti CD19-induced (Ca(2+))i signals are similar to the sIgM or sIgD-mediated signals in that they are inhibited by prior treatment with phorbol 12-myristate 13-acetate. However, LMW-BCGF- and CD19-mediated signals do not depend on the expression of sIg, since they were also observed on sIg-B-cell precursor acute lymphoblastic leukemia (ALL) cells. Both anti-CD19 and LMW-BCGF stimulated in vitro colony formation by ALL cells and showed additive effects when used together. (Ca(2+))i responses to LMW-BCGF or CD19 crosslinking were also evident on certain pre-B-cell and lymphoma B-cell lines. Keywords: B-cell activation, Signal transduction, Indo-1, Leukemic progenitor cells, Immunology, Reprints. (aw)