Cross-linking of the surface immunoglobulin on lymphocytes from the bursa of Fabricius results in second messenger generation.
The bursa of Fabricius represents the major site of B lymphocyte development in avian species. Although the vast majority of bursal lymphocytes express cell surface immunoglobulin (sIg), it is generally considered that the bursa does not represent a significant site of antigen-induced B cell maturation to Ig secretion. However, the question as to whether antigen, either exogenous or self, can induce positive or negative selection of bursal lymphocytes in such a way as to modify the peripheral B cell repertoire remains open. Clearly, such intrabursal selection would require that bursal lymphocyte sIg have the molecular machinery to transduce signals into the cell as a consequence of its interaction with antigen. In this report we demonstrate that exposure of bursal lymphocytes to antibodies directed against sIg induced a rapid increase in cytosolic free calcium ion concentrations [Ca2+]i. Furthermore, such antibodies also induced a rapid increase in intracellular phosphatidic acid concentrations followed by a rise in intracellular phosphatidylinositol. Increased [Ca2+]i, phosphatidic acid and phosphatidylinositol levels required the cross-linking of sIg and were not induced by antibodies to other bursal cell surface antigens. Thus, cross-linking of the sIg on bursal lymphocytes results in second messenger generation, demonstrating that bursal sIg is a functional signal transduction element.
Ratcliffe
M J
MJ
Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada.
Tkalec
L
L
D000818:Animals; D000888:Antibodies, Anti-Idiotypic; D000911:Antibodies, Monoclonal; D002060:Bursa of Fabricius / Q000166:cytology / Q000276:immunology*; D002118:Calcium / Q000378:metabolism; D002645:Chickens; D066298:In Vitro Techniques; D010712:Phosphatidic Acids / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism*; D015290:Second Messenger Systems / Q000276:immunology*; D015398:Signal Transduction / Q000276:immunology
D000888:Antibodies, Anti-Idiotypic; D000911:Antibodies, Monoclonal; D010712:Phosphatidic Acids; D010716:Phosphatidylinositols; D011947:Receptors, Antigen, B-Cell; D002118:Calcium