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.
|Number of pages||11|
|State||Published - Oct 1 1987|
Bibliographical noteFunding Information:
The authors thank Ms. Becky McCarthy and Ms. Theresa Burke for their expert technical assistance, and Drs. A. M. Kaplan, T. L. Roszman, and B. Subbarao for their critical reviews of this manuscript. This project was supported by Grants HL27333 from the National Institutes of Health and BC-434 from the American Cancer Society. S. A. Grupp is supported by NIH Molecular and Cellular Biology Training Grant HL07527. E. C. Snow is supported by Public Health Services Grant AGO476 10 1. J. A. K. Harmony is an Established Investigator of the American Heart Association.
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