Binding of bacterial lipopolysaccharide to murine lymphocytes.
Does LPS activate lymphocytes by binding to a specific cell-surface receptor or by nonspecific hydrophobic interaction with the plasma membrane? We examined this question by detecting cell-bound LPS using immunofluorescence microscopy and radiobinding techniques. LPS binding to splenic lymphocytes from C3H/St mice has characteristics of specific binding: saturability with respect to dose and time, selectivity for a subclass of B-cells, and a correlation between binding and mitogenesis. 125I-labeled LPS bound to cells and analyzed quantitatively by SDS-PAGE separated into 3 major components: peaks 1, 2, and 3 (1 equals the fastest moving). Lymphocytes preferentially bound peak 1, murine RBC peaks 1 and 2, and macrophages peak 2. In contrast, specific antibody preferred peaks 2 and 3. Differential staining of gels suggested that peak 3 is carbohydrate-rich and peak 1 is lipid-rich. LPS was released from these cells at different rates. We conclude that selectivity of LPS binding may be reflected in preferential binding of LPS subunits of different size and/or composition, as well as differential retention of bound LPS.
D000818:Animals; D000942:Antigens, Bacterial / Q000276:immunology; D001402:B-Lymphocytes / Q000145:classification / Q000276:immunology / Q000378:metabolism*; D001665:Binding Sites; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes / Q000032:analysis; D004926:Escherichia coli / Q000276:immunology*; D005455:Fluorescent Antibody Technique; D008070:Lipopolysaccharides / Q000032:analysis / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008809:Mice, Inbred C3H; D019081:O Antigens; D011869:Radioligand Assay; D011947:Receptors, Antigen, B-Cell / Q000032:analysis
D000942:Antigens, Bacterial; D000939:Epitopes; D008070:Lipopolysaccharides; D019081:O Antigens; D011947:Receptors, Antigen, B-Cell