T-cell regulation of human B-cell activation. A reappraisal of the role of interleukin 2

Abstract

The polyclonal activator pokeweed mitogen (PWM) has been widely used to study regulatory mechanisms in the differentiation of human B cells into immunoglobulin (Ig) secreting plasma cells (for review see Ref. 1). PWM-induced proliferation and differentiation of human B cells is strictly T-cell dependent and may provide a means to study the immunoregulatory activities of T-cell subsets 1–3. Furthermore, several antigen-non-specific T-cell derived factors have been shown toregulate B-cell activation 4,5. One class ofsolublefactors, designatedB-cellgrowthfactors(BCGF), supports growth of human B cells, when pre-activated by anti-Ig antibody or Staphylococcus aureus Cowan strain I(SAC) 4,5. A second class offactors, B-cell differentiation factors (BCDF) induces terminal differentiation of activated B cells into Ig secretingplasma cells 5. Here Frank Miedema and Cornelius Melief examine the claims and counterclaims concerning the influence of interleukin 2, a T-cell growth factor, on B cells and conclude that interleukin 2 has a pivotal role in the humoral immune response. The role of Interleukin-2 (IL-2) in B-cell activation is still controversial. Although a direct effect of IL-2 on resting murine B cells has been suggested by some investigators 6,7, others claim that IL-2 did not act on resting murine B cells 8–10.