Acute graft-versus-host reaction in mice. I. Cellular events.

Cellular events in the spleen during the development of acute GvH reaction in lethally irradiated recipients of allogeneic lymphocytes may be divided into 6 interrelated processes: (1) entering and lodging in the spleen of about 17% of inoculated cells which forms the compartment of potentially reactive cells; (2) transformation (recruitment) of about 30% of cells lodged in the spleen into large pyroninophilic cells (LPC), a process lasting about 12-16 hr; (3) proliferation of recruited LPC by five successive divisions with a Tc of about 12 hr; (4) transformation of LPC into non-LPC; (5) proliferation of non-LPC by one division, with a Tc of about 8 hr; and (6) migration of mature immunologically active cells from the spleen. The last process correlates well with the concomitant appearance of lymphocytes in the peripheral blood (killer cells) and with the time of acute death among inoculated mice.