The use of the natural binding of bacteria for the identification of human T- and B-lymphocyte subpopulations in blood smears

Abstract

In previous studies we showed that human Ig-bearing lymphocytes can be identified in blood smears by using anti-Ig antibody coated on a strain of Escherichia coli. We also showed that in purified lymphocyte suspensions, B cells and four T-cell subpopulations could be identified by spontaneous binding of several strains of bacteria. Here we investigated the possibility of identifying the lymphocyte subpopulations in blood smears by spontaneous binding of bacteria. Eight strains of bacteria were used: E. coli (Ec) 2 and 3, Arizona hinshawii (Ah), Bacillus globigii (Bg), Brucella melitensis (Bm), Staphylococcus aureus (Sa) 1 and 2, and Sarcina lutea (Sl). We determined the percentages of lymphocytes that bound these bacteria in blood smears from eight normal donors. The washed whole blood cells were centrifuged with bacteria, the excess bacteria were removed by low-speed centrifugation, and the smears were prepared and stained. We found that, in terms of percentages of lymphocytes labeled, bacteria bound consistently in normal donors. Also we mapped the lymphocyte subpopulations of three normal donors by labeling the lymphocytes with one strain or combinations of two strains of bacteria. Four T-cell and two B-cell subpopulations were identified. A minimum of four bacteria were shown to be sufficient to identify all these six subpopulations, which may be defined as follows: Bm + (B cells), Bm +Bg − (B 1), Bm +Bg + (B 2), Bm −Ah +Bg − (T 1), Bm −Ah +Bg + (T 2), Bm −Ah −Sal + (T 3) and Bm −Ah −Sal − (T 4). We concluded that in normal donors six lymphocyte subpopulations consistently can be identified by labeling the lymphocytes in blood smears with at least four strains of bacteria.