Enumeration in whole peripheral blood of lymphocytes bearing receptors for Fc(gamma) and C3b using alkaline phosphatase-labelled reagents.

The whole blood method for enumeration of T and B lymphocyte populations using alkaline phosphatase-labelled reagents (Druguel and Pepys, 1977) has been extended to the quantitation of lymphocytes bearing receptors for Fc(gamma) and for C3b. This technique, by avoiding the variable loss of cells which is unavoidably associated with separation of mononuclear cells from blood, permits accurate measurement of the proportions and absolute numbers of circulating lymphocytes bearing these receptors. Fc(gamma) receptors were detected using complexes of alkaline phosphatase (AP) and eluted rabbit IgG anti-AP antibody. Receptors for C3b were detected using isolated human C3b followed by conjugates of AP with F(ab)2 of sheep anti-human C3 antibody. The mean +/- S.D. of Fc(gamma) receptor-positive lymphocytes among 16 normal adults was 11.8 +/- 2.5%, 248 +/- 113/microliter and among 17 normal adults the values for C3b receptor-positive lymphocytes was 9.4 +/- 2.0%, 208 +/- 101/microliter.