Ligation of CD45 on B cells can facilitate production of secondary Ig isotypes.
The possibility that isotype switching in B cells may be affected by engagement of the CD45 molecule on B cells has been investigated in microcultures containing limiting numbers of B cells and nonlimiting numbers of both alloreactive Th cells and purified dendritic cells (DC). Addition of Abs to the B cell-specific isoform, B220, to the microcultures leads to an increase in the proportion of B cell clones that secrete secondary Ig isotypes. In the presence of anti-CD45 Ab, microculture wells show a 39% frequency of secondary isotypes (560/1440) compared with a 11% frequency in control microcultures (89/780). Cross-linking appears to enhance this effect. Even in cultures of B cells and DC without T cells, addition of anti-B220 induces isotype switching in a significant number of microwells. Cross-linking and capping B220 molecules results in co-capping of surface Ig and MHC class II molecules. The results suggest that signal transduction through the CD45 molecule may affect pathways involved in isotype switching.
George
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A
Department of Biology, University of Pennsylvania, Philadelphia 19104.
Rath
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S
Shroff
K E
KE
Wang
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M
Durdik
J M
JM
D000818:Animals; D016175:B-Lymphocyte Subsets / Q000276:immunology*; D003713:Dendritic Cells / Q000276:immunology; D007072:Immunoglobulin D / Q000378:metabolism; D007132:Immunoglobulin Isotypes / Q000096:biosynthesis*; D007152:Immunologic Capping; D017493:Leukocyte Common Antigens / Q000502:physiology*; D008211:Lymphocyte Cooperation; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D011940:Receptor Aggregation; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology
D007072:Immunoglobulin D; D007132:Immunoglobulin Isotypes; D011947:Receptors, Antigen, B-Cell; D017493:Leukocyte Common Antigens