Frequency of B cells in normal mice which recognize self proteins

Abstract

The mechanism whereby the immune system avoids self-aggression is one of the central issues of Immunology. The discovery of natural autoantibodies, mainly of IgM isotype, and of idiotypic interactions between antibodies indicates that elements of the immune system interact with self constituents and with themselves. Results of studies with soluble antibodies have indicated that the pool of circulating IgM represents the end result of a highly selective process of B cell activation and differentiation by self proteins resulting in the formation of a network. The objective of the present work was to determine the frequency of self-reacting B cells in normal mice. We were able to detect B cells that recognize self proteins present in extracts of different organs in normal adult, 2-3-month old, BALB/c and C57BL/ 6 mice with an ELISA spot assay. About 1% of total IgM-secreting cells among small, LPS-stimulated spleen cells reacted with organ extracts, whereas among large spleen cells the frequency was 5-to 10-fold lower. Immunization induced an increase in the frequency of IgM-secreting cells. The present results provide cellular evidence for the results of studies done at the serological level. The physiological role of these self-recognizing cells, as well as their participation in autoimmune processes, remain to be established.

In Search of the In Vivo Identity of Mesenchymal Stem Cells

“…Furthermore, MSC effects on immune system cells would be important in tissue repair (described below). Participation of MSCs/pericytes in self-tolerance maintenance by exerting immunosuppressive effects would adequately explain why autoimmune reactions are not frequent in spite of the existence of self-reactive lymphocytes [161]. Likewise, some autoimmune diseases may reflect an intrinsic or genetic impairment of this immunosuppressive capacity of MSCs/pericytes.…”