Expression of the p70 chain of the IL‐2 receptor on human lymphoid cells: Analysis using a monoclonal antibody and high‐sensitivity immunofluorescence

Using monoclonal antibody (MoAb) against the p70(β)chain of the interleukin‐2 receptor (IL‐2R) and a high‐sensitivity immunofluorescence procedure, p70 can be demonstrated on the majority of lymphocytes from normal blood samples, without in vitro stimulation. A subpopulation of cells bears a high concentration of receptor, and these cells have the physical properties of large granular leucocytes (LGL). The smaller lymphocytes, although weaker, are quite clearly positive T8 cells stain relatively strongly, while T4 cells and B cells slain relatively weakly. Leukaemic cells showed a variety of phenotypes when examined for expression of the p55 and p70 chains of the IL‐2R. The demonstration of IL‐2R chains directly by immunofluorescence on unstimulated lymphocytes has potential clinical applications, since this technique can be used in a diagnostic setting.