title: Lipid synthesis: an indicator of antigen-induced signal transduction in antigen-binding cells.
abstract: A biochemical parameter of lymphocyte activation, lipid synthesis, has been measured in a purified specific antigen-binding cell population (ABC). ABC isolated form immune and nonimmune animals by sequential centrifugation on buoyant density and sedimentation velocity gradients have a 2- to 7-fold higher rate of 14-C choline incorporation into phospholipid than either unfractionated spleen cells or cells depleted of ABC. Aslo ABC from immune animals were shown to have a 4- to 7-fold higher rate of 14C-acetate incorporation into their neutral lipids than nonbinding controls. The elevated lipid synthesis seen in both nonimmune SRBC-ABC and TNP-SRBC ABC indicates that antigenic contact via the B cell immunoglobulin receptor results in signal transduction and activation of the specific receptor-bearing lymphocyte population. Binding of the same particle (SRBC) to B cells via their Fc receptors did not regularly result in activation of lipid synthesis. The magnitude of the increased lipid synthesis in ABC populations approached that seen in LPS-stimulated spleen cells. We propose that the measurement of early activation events in purified ABC may be a more appropriate criterion for antigen-induced signals that later events such as thymidine incorporation or antibody secretion.
mesh_terms: D000818:Animals; D000941:Antigens; D001665:Binding Sites; D002794:Choline / Q000378:metabolism; D004912:Erythrocytes / Q000276:immunology; D005260:Female; D006462:Hemolytic Plaque Technique; D007141:Immunoglobulin Fc Fragments; D008055:Lipids / Q000096:biosynthesis*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000276:immunology*; D051379:Mice; D008808:Mice, Inbred CBA; D010743:Phospholipids / Q000096:biosynthesis; D012756:Sheep; D013154:Spleen / Q000276:immunology
chemical_list: D000941:Antigens; D007141:Immunoglobulin Fc Fragments; D008055:Lipids; D008070:Lipopolysaccharides; D010743:Phospholipids; D002794:Choline