title: Chlamydia trachomatis (L2 serovar) binds to distinct subpopulations of human peripheral blood leukocytes.
abstract: We have previously shown that infants with pneumonitis caused by Chlamydia trachomatis, an obligate intracellular bacterium, possess increased percentages of B lymphocytes but not T lymphocytes in their peripheral blood. It was then demonstrated that chlamydiae induce proliferation in vitro of human peripheral blood B lymphocytes and, in the presence of T cells, differentiation of B cells to immunoglobulin-secreting cells. In this study, we show that C. trachomatis (L2 serovar) binds preferentially to 50% of human B lymphocytes from peripheral blood but only to a small percentage, if any, of T cells. Both monocytes and granulocytes bind and ingest chlamydiae. Despite chlamydial binding to B cells and ingestion by monocytes, no uptake by B cells and limited growth (fewer than 0.5% inclusion-containing cells) in monocytes occur. There is a dramatic decrease in the percentage of cells associated with the bacteria after culture. These results are the first demonstration of binding of C. trachomatis (L2 serovar) to lymphocytes and represent a direct step toward correlating physical interactions between bacteria and lymphocytes with specific immunostimulatory activities in vitro.
mesh_terms: D000268:Adhesiveness; D000328:Adult; D001402:B-Lymphocytes / Q000276:immunology / Q000382:microbiology; D002478:Cells, Cultured; D002692:Chlamydia trachomatis / Q000254:growth & development / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D006098:Granulocytes / Q000382:microbiology; D006801:Humans; D007962:Leukocytes / Q000145:classification / Q000382:microbiology*; D008213:Lymphocyte Activation; D009000:Monocytes / Q000382:microbiology; D013601:T-Lymphocytes / Q000382:microbiology