Subsets of normal mononuclear cells in the peripheral blood defined by monoclonal antibodies.

We studied the peripheral blood of 20 healthy adult individuals for the distribution of subsets within the mononuclear cell population using indirect immunofluorescence staining. Normal ranges are given for several cell populations reacting with a panel of monoclonal antibodies. The analyzed immunological reagents included the monoclonal antibodies Leu-1 (Pan-T), Leu-2a (Suppressor-T), Leu-3a (Helper-T), Leu-7 (Natural Killer-T), MCS-2 (Pan-myeloid), NU-B1 (Pan-B), FMC-7 (B-subset), Tac (IL-2-receptor) and sheep erythrocyte rosetting (E). Cells were examined for positivity under an epi-immunofluorescence microscope and by flow cytometry. The data obtained by these two different approaches were in close agreement. The majority of the cells from the total mononuclear cell fraction in the peripheral blood were Leu-1+ (mean value of 64% by microscope/59% by flow cytometry) and E+ (61%). The T-populations could be broken down into Leu-3a+ (48%/43%), Leu-2a+ (31%/31%) and Leu-7+ (13%/14%). Between 2 and 5% of the cells showed double expression of antigens detected by Leu-2a and Leu-3a. The pan-myeloid reagent MCS-2 was positive on 25%/18% of the total cell population; the B-cells accounted for 5%/8%. Tac stained 7%/6% of the cells.