Formation of B Lymphocytes in Fetal and Adult Life

Abstract

Publisher Summary were regarded Lymphoid and hematopoietic stem cells are highly specialized and antigens recently identified by several laboratories may be useful in resolving categories and stages of differentiation. This chapter discusses some procedures that may not only allow the differentiative potential of B-cell precursors to be assessed but provide some insight into the inductive signals and regulatory mechanisms involved. The extraordinary progress of experimental hematologists in resolving the precursors of erythroid and myeloid cells has created a false sense of understanding about the nature and fate of stem cells relevant to the humoral immune system. The time when B cells or their precursors first appear during ontogeny or during regeneration of irradiated animals, they are diluted among nonlymphoid hematopoietic cells. The use of cytoplasmic immunoglobulin as a marker for pre-B cells and various cell surface antigens are discussed. Cells dissected from spleen colonies have been used to restore humoral immunity to irradiated secondary recipients, and the time required was because of transition of stem cells. Extensive examinations of spleen colonies have not revealed any that had predominantly lymphoid morphology. However, the possibility of a minor entry of stem cells into B and T pathways would be difficult to rule out, particularly if the newly formed cells rapidly migrated elsewhere.