B lymphocytes from individuals with common variable immunodeficiency respond to B lymphocyte stimulator (BLyS protein) in vitro.

B lymphocyte stimulator (BLyS protein) is a member of the human TNF family of ligands. BLyS induces B-lymphocyte proliferation and Ig secretion in vitro and in vivo. These qualities suggest that it may be useful as a therapeutic in the treatment of immunodeficiencies characterized by low or absent serum immunoglobulin, such as common variable immunodeficiency (CVID). CVID is characterized by the inability to generate adequate serum Ig despite normal or slightly depressed peripheral B, T, and myeloid cell populations. We tested the ability of BLyS to stimulate B lymphocytes obtained from CVID patients. Among five patients studied, 60% (three of five) produced normal quantities of IgM when cultured in the presence of BLyS. B-cell proliferation among patients was comparable, with 60% (three of five) responding to BLyS stimulation. These results suggest that BLyS induces proliferative and Ig-secretory responses in B lymphocytes isolated from some CVID patients and lend support to its potential use in therapy of this disorder.