Study on the Effect of Calf Thymic Peptides Preparation (Tp) on Human B' Lymphocytes

Abstract

Extensive experimental evidence has shown that thymic hormones (or factors) affect and regulate the differentiation and function of T lymphocytes. However, little is known about the action, if any, of thymic hormones on B lymphocytes. This paper reports the results of an investigation of the effect of a calf thymic peptide preparation (TP) prepared in our laboratory, on the proliferation and differentiation of human B lymphocytes. TP at concentrations higher than 1 micrograms (protein)/ml inhibited the proliferative responses of human B lymphocytes to the stimulation by Staphylococcus aureus Cowen strain I (SAC) and F(ab')2 fragments of goat anti-human IgM, mu chain specific antibody (anti-mu). TP itself had neither toxic nor mitogenic effect on B cells. TP at concentrations of 60 and 100 micrograms/ml did not affect the differentiation of B cells driven by SAC and PWM in a reverse PFC assay, but appeared to suppress the production in some individuals of total IgG and IgM in culture supernatants in a PWM system. Preculture of B cells with 60 micrograms/ml of TP for 40 hrs showed a suppression of the proliferative response to SAC and anti-mu stimulation, suggesting that TP might act on cells directly and persistently for some time. When TP was added to the culture on day 0 or on day 1, a similar decrease of inhibition of B cell proliferation was observed. A decrease in monocytes from 15-17% to 5% did not appreciably influence the suppression of SAC- or anti-mu-induced proliferation of B cells by TP. These preliminary results suggest that a calf thymic peptides preparation might have some direct effect on B lymphocytes.