Biochemical characterization and immunomodulatory action of thymic components as determined by flow cytometry on human lymphocytes.

A commercial preparation from calf thymus was separated into its components, then chemically characterized and tested for immunomodulatory efficiency. For the latter, a novel in vitro test system is described as a relatively simple screening procedure. It employs whole blood cultures and flow cytometry with fluorescent monoclonal antibodies defining human T-cell subsets. As a reference substance, thymosin fraction 5 was used. It could be shown that the effects of the entire thymic preparation as well as of one of its peptidic components resembled closely the ones obtained with thymosin fraction 5. In several cases, i.e. with donors relatively deficient in suppressor/cytotoxic T-lymphocytes, the effect of the former was even superior to that of thymosin fraction 5.