Inhibitory action of pig alpha-fetoprotein through early activated thymocyte surface Na+, K+-adenosinetriphosphatase.

An immunomodulatory effect of pig alpha-fetoprotein (AFP) on early phytohaemagglutinin (PHA)-stimulated intact thymocytes from piglets was analyzed. The activity of surface-localized Na+, K+-adenosinetriphosphatase was estimated, as the early reaction of mitogen-stimulated T-lymphocytes. A high inhibition of PHA-stimulated enzyme activity was found in the presence of AFP. The reaction was dependent of PHA concentration when using a constant AFP concentration. The highest AFP-induced decrease in PHA-induced Na+, K+-ATPase activity was 72%. AFP was isolated by a new technique based on salting out in ammonium sulphate and acetate buffer solutions. A gentle, simple and rapid procedure makes it possible to obtain AFP in a high degree of purity with preserved biological activity. The presented results can contribute to understanding the molecular aspects of AFP immunoregulation of lymphocyte reactivity in vitro.