INFLUENCE OF TRANSFORMING GROWTH-FACTOR-BETA (TGF-BETA) ON THE IMMUNOGLOBULIN PRODUCTION BY EBV-INFECTED B-CELL CULTURES

TGF-beta inhibits the proliferation of human B lymphocytes stimulated by a variety of activators, including EBV. However, EBV-immortalised c ells are refractory to TGF-beta. The influence of TGF-beta on B cell m aturation varies, apparently depending on the origin of the B lymphocy tes and their maturation/activation state, the strength of the stimulu s and the presence of cofactors. We investigated the effect of TGF-bet a on immunoglobulin production by 5-day-old EBV-infected B cells. TGF- beta added at the initiation of the cultures inhibited IgM, IgG and Ig A secretion by decreasing the numbers of secretory cells. The inhibiti on of IgM secretion was strongest. At the cytoplasmic level, TGF-beta reduced the expression of IgM heavy, lambda and kappa light chains but not IgG and IgA heavy chains. However, the IgM production by an estab lished EBV-transformed B cell line was not affected by TGF-beta. Thus, TGF-beta inhibited EBV-induced maturation of the B cells until they a cquired a transformed state. We discuss the relevance of these finding s for the potential role of TGF-beta on EBV infection.