The spleen in acquired immunodeficiency syndrome (AIDS).

72 spleens from AIDS patients were studied by histologic and immunohistochemical methods. Apart from the opportunistic infections and malignancies typically occurring in AIDS patients (malignant lymphomas, Kaposi's sarcoma, mycobacterial infections, cryptococcosis, cytomegalovirus infections) morphological changes probably directly attributable to HIV infection were noted that progressed from follicular hyperplasia with nearly normal periarteriolar lymphoid sheaths to atrophy of follicles and severe cellular depletion of T cell areas with concomitant plasmacytosis and occurrence of small giant cells. At the same time the number of Protein S-100 positive cells markedly increased; in some cases almost all pulp cord macrophages expressed the antigen. In addition, the sinus endothelia strongly expressed protease inhibitors.