Thymic function in man

Thymic function in man, characteristics of thymic hormones (thymosin fraction V, thymosin α₁, thymopoietin II, thymic humoral factor, and facteur thymique serique) and its role in T cell precursor differentiation are reviewed. An analysis is also performed on the biological, immunological and morphological changes observed within the gland in severe combined immunodeficiencies. The therapeutic value of thymic hormones is analysed when applied to very diverse types of combined immunodeficiencies. At present, the results reached by fetal thymus transplants in primary immunodeficiency are very irregular, being usually in accordance with the degree of the immunodeficiencies. The most positive results are seen in a number of cases of DiGeorge syndrome (9 out of 10 transplants responded positively). Less positive results appeared in 12 cases of severe combined immunodeficiency, and in mucocutaneous candidiasis. Contradictory results were obtained in Wiskott-Aldrich syndrome and ataxia-telangiectasia. A review is also given on the therapeutic value of implants of cultured thymic epithelium for such immunodeficient syndromes (Lombart-Bosch, Valencia).