Expression of IL-2 receptor p55 and p75 chains by human B lymphocytes: effects of activation and differentiation.

Whilst B cells in human blood can be shown to express interleukin-2 receptor (IL-2R) p55 and p75 chains, using a high-sensitivity immunofluorescence procedure, fresh tonsil B cells did not show detectable levels of expression. Culture of tonsil B cells led to low levels of expression of the p55 chain of the IL-2R, an effect which was dependent on protein synthesis. The level of expression of IL-2R chains could be modulated by culturing in the presence of a number of factors which activate B cells. p55 levels were more readily modulated than p75 levels. IL-4 and combinations of IL-4 with anti-IgM, IL-2 or tumour necrosis factor-beta (TNF-beta) modulated p55 levels, but IL-5 did not. Changes in IL-2R expression were small when compared with other B-cell activation markers such as CD23. When unfractionated tonsil cells were activated with a polyclonal stimulus, the major change was the expression of p55 by T-cell blasts--p75 expression remained low in T and B cells, and p55 expression by B cells remained low.