Molecular signals for the production of lymphocytes in bone marrow

Bone marrow culture and molecular cloning techniques have permitted rapid progress to be made in identifying molecules that stimulate or inhibit particular steps in blood cell formation. Two types of factors that influence B lymphocyte precursors are considered in this brief review. Cell adhesion molecules are probably needed to correctly position immature precursors within the marrow and some of the most important of these have been identified. Recent studies suggest that local or systemically derived hormones must also be added to the list of agents which can markedly influence the production of lymphocytes.