Oligoclonal Development of B Cells Bearing Discrete Ig Chains in Chicken Single Germinal Centers

Chicken single germinal centers enable us to analyze the postbursal diversifications of B cells due to their easy isolation. Germinal center formation has peaked by day 7 of primary responses and begins to wane 14 days after immunization. To detail the kinetics of Ig mutation and selection, we analyzed Ig light chain sequences recovered from single germinal centers at 7 and 11 days postimmunization with an artificial Ag. Our observations show that multiple, Ag-activated B cells migrating into single germinal centers are diversified by gene conversion in the very early phase of the germinal center reaction and are subsequently subjected to point mutations and selection for oligoclonality.