Role of the Thymus in the Recovery of Hemolytic Plaque Formation After X-Irradiation 1

Abstract

Summary

Relationship between hemolytic plaque formation and repopulation of spleen and thymus after X-irradiation was studied by using two substrains of CBA mice. The CBA/H and CBA/St mice generated almost equal numbers of hemolytic plaques in the spleen at 7 days after intraperitoneal injection of sheep red blood cells (SRBC). The CBA/St mice that received 400 R of wholebody irradiation, or 600 R of irradiation and injection of 5 X 10⁶ marrow cells, generated smaller numbers of plaques at days 22 and 29 than did CBA/H mice that received the same treatment. Bone marrows, thymuses, and spleens of sham-thymectomized and thymectomized CBA/H and CBA/St mice were almost exclusively repopulated with donortype cells by day 22.

Donor-type cells in the spleens of CBA/H mice had been “instructed” in the thymus, were seeded to the spleen, and responded to antigens, but the spleens of CBA/St mice which were also repopulated with donor marrow cells, had very small numbers of these instructed cells that were capable of responding to antigens.