PHENOTYPIC AND FUNCTIONAL ALTERATIONS OF THYMIC NURSE CELLS FOLLOWINGACUTE TRYPANOSOMA-CRUZI INFECTION

Acute Trypanosoma cruzi infection induces alterations in both lymphoid and microenvironmental compartments of the thymus. This prompted us t o investigate whether the lymphoepithelial complex thymic nurse cell ( TNC) was comprised in the thymic pathology occurring in experimental C hagas' disease. The isolation of TNCs from acutely T. cruzi-infected m ice revealed a reduction in TNC numbers that paralleled thymic atrophy . This decrease does not seem to be stress-related since it was not se en following glucocorticoid hormone injection. Moreover, an increased intra-TNC cell death in complexes hom infected animals was noticed. In addition, acute T. cruzi infection induced a decrease in size and gra nularity of TNC complexes, as well as several ultrastructural alterati ons indicating cell damage. The epithelial component of TNCs, independ ent of being infected in vitro or derived from infected animals, showe d an enhancement of extracellular matrix proteins that is likely relat ed to the enhanced thymocyte release observed in these complexes. Conj ointly, these data show that TNCs are importantly affected in acute ex perimental T. cruzi infection, possibly contributing to the previously observed alterations in thymocyte differentiation. (C) 1997 Academic Press.