Germinal centres and the B-cell system. V. Presence of germinal centre-precursor cells among lymphocytes of the thoracic duct in the rat.

Thoracic duct lymphocytes (TDL) were studied with respect to their capacity to give rise to germinal centres (GC) and to form primary antibody in an adoptive transfer system of the rat. Challenge with sheep erythrocytes (SRBC) 24h after lethal irradiation (900 rads) and syngeneic TDL reconstitution (10(8)) lead to conspicuous GC activity already 7 days after transfer. In contrast, using syngeneic bone marrow (BM) in the adoptive transfer system, no GC formation was observed over the period studied (14 days after reconstitution). Reconstitution experiments using in vivo-separated T-TDL (1-5% s-Ig+) and B-TDL (greater than 90% s-Ig+) subpopulations, either separately or in combination, indicated that GC originate from B-TDL but require T-TDL for induction.