Thymic Hormones in Viral Infections and Aids

Thymic hormones participate in T-cell differentiation in all three lymphoid cell compartments: bone marrow, thymus gland, and peripheral lymphatic system. These hormones play an essential role in the stepwise process of differentiation and maturation of thymocytes and of T-cells in the absence of antigenic stimulation, thus contributing to a balance between subsets of T-helper, T-cytotoxic and T-suppressor cells (1). Viruses, on the other hand, may cause a disarrangement of the lymphoreticular system, the seriousness of which depends on the aggressiveness of the virus involved. Indeed, following infections such as measles, rubella, cytomegalovirus and dengue, the respective viruses have been detected in peripheral circulating lymphocytes (2). During the course of the infection, viruses may destroy lymphoid cells directly or may persist in the lymphoreticular system leading to the alteration of cellular immune functions. These observations, taken together, led us to formulate the hypothesis that thymic hormones may represent a valuable tool in the therapy against a variety of pathogenic viruses. Without aiming at an exhaustive review of this subject, we present our experience with thymic humoral factor (THF) and most of that obtained by now with other thymic hormone preparations, in the struggle against viral infection in humans.