Diminished Synthesis of Immunoglobulins by Lymphocytes of Patients Treated with Thymosin (TFX) and Cyclophosphamide

Abstract

Thymosin fraction V, one of the most important hormonal-like peptides produced by the thymus, has been shown to be a useful agent in treating patients with primary and secondary immunodeficiency diseases (4). Thymus Factor X (TFX), an extract corresponding to thymosin fraction V prepared from calf thymus by Polfa Pharmaceuticals (Jelenia Góra, Poland) has been found to have similar immunomodulating properties (3). Thymic factors participate in the process of immune regulation by affecting the functions of various T lymphocyte subsets. Therefore, it may be anticipated that the final effect of their action depends on a number of factors including the immune status of a patient and the conditions of administration. This may explain why a thymic factor can cause opposing effects in vitro, and when administered in vivo, may lead to both amelioration and aggravation in the same clinical situation (15). We have recently shown that TFX is a potent inducer of helper T cells for antibody production in man. However, when TFX is added to lymphocytes generating high numbers of plasma cells in culture the resulting immunoglobulin synthesis is markedly reduced (7, 8). This data indicates that in some situations thymosin could have immunosuppressive properties. This further suggests the feasibility of combining TFX with immunosuppressive drugs which might be a more efficient immunosuppressive protocol to inhibit humoral responses.