The Histopathological Changes in the Thymus Gland in the Acquired Immune Deficiency Syndrome

Histologic study of the thymus glands from patients who have died of AIDS reveals changes consistent with an organ-specific immune complex attack by polyclonal immunoglobulins directed against the thymic epithelial cells, Hassall's corpuscles, and certain subsets of thymocytes. This results in marked architectural alteration: there is eventual disappearance of the corpuscles, the epithelial cells become spindled with pyknotic nuclei, there is thymocyte depletion and patchy fibrosis, and there is loss of the normal corticomedullary demarcation. These changes are characteristic and are not found in the normal aging process of the thymus gland. The blood levels of thymic peptides are abnormal. There appears to be specific immunoglobulins directed against thymic epithelial cells, Hassall's corpuscles, and certain subsets of T lymphocytes. The end result appears to be both a histologic and functional thymic disorder. If this is correct, then appropriate therapy for AIDS may be thymic peptide replacement or even thymic transplantation.