THYMIC EPITHELIAL INJURY IN GRAFT VERSUS HOST REACTIONS FOLLOWING ADRENALECTOMY

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  • 1 January 1978
    • journal article
    • research article
    • Vol. 93  (2) , 325-338
Abstract
In 4 separate experiments 140 adult A(H-2a) .times. C57BL/6 (H-2b) F1 hybrid mice were surgically adrenalectomized and divided into 3 experimental groups. Seventy-one additional adult F1 hybrids (AXC57BL/6) which were not adrenalectomized were divided into 3 similar groups. In Group 1 (GvH [graft vs. host] group), GvH reactions were induced by the injection of 50 .times. 106 pooled parental lymphoid cells i.v. The 2nd group (syngeneic group) received 50 .times. 106 pooled F1 hybrid lymphoid cells i.v. The 3rd group (uninoculated group) received no lymphoid inoculum. At regular intervals the animals were killed, autopsied and histologically studied. Visceral alterations of GvH reaction were recorded in the thymus, lymph nodes, spleen and liver in the GvH groups; none was present in the other groups. The thymuses in the nonadrenalectomized GvH group underwent prompt involution characterized by size reduction and cortical lymphoid cell depletion. These changes were not apparent in the GvH adrenalectomized group. Both GvH groups demonstrated an effacement of the medulla, lymphocyte incursion into the medulla, lymphocyte emperipolesis of medullary epithelial cells, gradual disappearance of hassall''s corpuscles, epithelial cell injury and an ingress of macrophages laden with nuclear and cellular debris. The stress and corticosteroid response which accompany a GvH reaction may account for the reduction in the thymic size and cortical lymphoid cell mass. The medullary alterations appear to be initiated by the GvH reaction per se.