IMMUNO-SUPPRESSIVE EFFECT OF HUMAN ALPHA-FETOPROTEIN - A CROSS-SPECIES STUDY

Alphafetoprotein (AFP) is the major serum protein of fetal life in hum an and other mammalian species. The phylogenetical concervatism of AFP demonstrated by extensive immunological cross reaction between human AFP and AFP of a number of species, suggest that AFP plays a general r ole in the successful pregnancy of all mammalian species. The present work clearly demonstrates the antiproliferative effect of human AFP on lymphocytes, harvested from normal human donors. The inhibitory effec t of human AFP is quite significant in the same dose during blastic tr ansformations of the lymphocytes. In this study, peripheral blood mono nuclear cells were induced to blastic transformations with phytohaemag glutinin (PHA-M) and the effect of AFP was quantified by the incorpora tion of [H-3]-thymidine into newly synthesized DNA during 24 hrs pulse . Moreover, human AFP shows similar immuno-suppressive effect to other species of lymphocytes also. In all the three species (mouse, rat and hamster) studied, a paralleism was noted in their respective percenta ge of thymidine incorporation values at the comparable doses. These re sults establish a cross species inhibitory effect of human AFP and it may be stated that this effect is directly targeted on T-helper cells and has no interaction with interleukin-2 (IL-2).