Binding of Bacteria to Lymphocyte Subpopulations

Abstract

Publisher Summary Both in humans and in mice, it has been possible to map the lymphocyte subpopulations using bacteria as specific membrane markers. All human B cells, normal or leukemic, bind Brucella melitensis as well as other human pathogens from the genus Brucella, while T cells do not bind these bacteria. By using four strains of bacteria, B. melitensis, A. hinshawii, B. globigii, and S. schottmulleri, in addition to B cells (Bm+), two B- and four T-cell subpopulations have been identified—which were given arbitrary numbers, B1, B2, and T1–T4. Three B cell subpopulations, B1–B3, and three T cell subpopulations, T1–T3, were identified in the mouse spleen using a minimum of four bacteria: B. melitensis, A. hinshawii, E. coli-2, and E. coli-3. As the function of B cells is definitely different from that of T cells, the existence of B. melitensis as a B cell marker suggested that the lymphocyte subpopulations identified by bacterial adherence are functionally different. Experiments with B. melitensis and with a mutant of E. coli suggested that there may be lectins on the lymphocyte membrane that interact with carbohydrates on the bacteria, an interaction that can be inhibited by certain monosaccharides or by the specific lipopolysaccharides (LPS). Bacteria bind consistently to lymphocytes, and their binding properties are not affected by heating or formaldehyde fixation. These properties have allowed their use as shelf reagents in stained smears prepared from peripheral blood or from bone marrow. The use of bacteria as markers of lymphocyte subpopulations is significant for a few reasons—bacteria are stable shelf reagents, easy to prepare, and store.. The use of bacteria in blood smears offers the possibility of morphologic examination of the lymphocytes and of obtaining a permanent record.