The phosphatidylinositol response is an early event in the physiologically relevant activation of antigen-specific B lymphocytes.
Receptor ligand-induced turnover of plasma membrane phosphatidylinositol (PI) has been implicated as part of a membrane receptor signal transduction system in a number of mammalian cell types. Signaling through B-lymphocyte surface immunoglobulin (sIg2) has been explored polyclonally through the use of anti-Ig reagents, with the assumption that anti-Ig mimics the process of antigen binding to the antigen-specific cell. We have utilized a method of obtaining trinitrophenyl (TNP)-specific populations of B lymphocytes in order to determine if antigen binding to these antigen-specific cells initiates PI turnover. This method has allowed us to explore the membrane phospholipid events following antigen binding directly, rather than with inference from the anti-Ig system. We have found that both thymus-dependent and thymus-independent antigens (with the exception of TNP-lipopolysaccharide) produced an increase in PI turnover comparable to that generated by anti-IgM stimulation. The lack of increased PI turnover following TNP-LPS stimulation may be attributable to the action of LPS on the biochemical events of the PI cycle. In a B-cell subpopulation depleted of antigen-specific cells, only anti-IgM produced a PI effect. These results represent the first demonstration of PI turnover as an early activation event in a physiologically relevant lymphocyte system.
D000818:Animals; D000941:Antigens / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C / Q000276:immunology; D010716:Phosphatidylinositols / Q000096:biosynthesis / Q000502:physiology*; D011947:Receptors, Antigen, B-Cell / Q000276:immunology*
D000941:Antigens; D010716:Phosphatidylinositols; D011947:Receptors, Antigen, B-Cell