Clonal dominance: loss and restoration in adoptive transfer.

An adoptive transfer system was used to study the mechanism responsible for clonal dominance of the anti-phosphorylcholine response in BALB/c mice. The adult spleen contains phosphorylcholine-specific precursor cells that are capable of developing into antibody-producing cells after transfer into lethally irradiated animals. The neonatal liver of the BALB/c mouse lacks precursor cells specific for phosphorylcholine but contains immature cells that differentiate into specific precursors during the normal course of ontogeny. The transfer of fetal or neonatal liver cells into lethally irradiated recipients prevents the appearance of the dominant H8 clone which constitutes the majority of the clones responding to phosphorylcholine in adult BALB/c mice. However, if these cells are transferred into neonatally suppressed recipients that lack the H8 idiotype, dominance of the H8 clone can develop. The conversion of the committed immature progenitor cell into a responsive B lymphocyte precursor is a regulated event. Regulation at the level of progenitor cells determines the eventual clonal profile of the immune response to phosphorylcholine. It is suggested that selection of the dominant clone occurs at this level.