The use of Salmonella schottmulleri for mapping and separation of human lymphocyte subpopulations.

Human lymphocyte subpopulations (B cells, B1, B2, T1, T2, T3, and T4 cells; our denomination) have been previously identified and isolated by bacterial adherence and functional differences between them have been demonstrated. Here we examined the binding properties of Salmonella schottmulleri to human lymphocytes in peripheral blood smears and found that it binds to more lymphocyte subpopulations, namely B, T1, T2 and T3 cells, than any bacteria previously tested. Thus, using only four bacteria: Salmonella schottmulleri, Brucella melitensis, Arizona hinshawii and Bacillus globigii we identified in blood smears B cells, two B and four T cell subpopulations. When we used gelatin-coupled monolayers of Sal. schottmulleri to isolate lymphocyte subpopulations, we showed that the nonadherent (T4) cells could be efficiently separated from the adherent cells. Furthermore, we tested the isolated subpopulations for natural killing (NK) activity and for antibody-dependent cell-mediated cytotoxicity (ADCC). Using both NK and ADCC assays, we observed a significantly higher cytotoxic activity in the nonadherent cell population than in the unseparated or adherent cell populations. Also the nonadherent cells contained most of the lymphocytes that have receptors for the Fc portion of IgG and those cells described as large granular lymphocytes. We concluded that Sal. schottmulleri is a valuable new reagent for the identification and separation of human lymphocyte subpopulations.