Thymic Microenvironment and Lymphoid Responses toSublethal Irradiation

摘要

Sublethal irradiation of the murine thymus has been a useful tool for depleting the thymusof dividing immature thymocyte subsets, to sequence thymocyte differentiation eventsoccurring from radiation-resistant precursors. This massive reduction in thymocytes alsorepresents a model in which the bidirectional interplay between the thymic stromal cellsand lymphocytes can be investigated. The purpose of this study was thus twofold: toprecisely map the initiation of thymopoiesis as a prelude to assessing the effects of injectedmAb to novel thymic antigens; and to use a panel of mAbs to determine the alterations inthe thymic stroma during the T-cell depletion and reconstitution phases. The strikingfinding from this study was that following T-cell depletion, there was a marked upregulationof specific stromal antigens, which retracted with the reappearance of T cells. Thus,following sublethal irradiation, there are modifications in the thymic microenvironment thatmay be necessary to support renewed thymopoiesis and the complete restoration of thethymus involved the synchronous development of both the stromal and lymphocyticcomponents.