The effect of human α1-acid glycoprotein (α1 AGP), α1-antitrypsin (α1AT), and haptoglobin (Hp) on lectin-induced lymphocyte transformation was examined in vitro. Alpha1-AGP had a suppressive effect on phytohemagglutinin (PHA)-induced lymphocyte response, while it tended to accelerate concanavalin A (Con A) and pokeweed mitogen (PWM)-induced response. Alpha1-AT inhibited Con A-induced response but had no effect on PHA- and PWM-induced response. Hp (type 2-2) markedly inhibited all of the three lectin-induced responses. In order to examine the mechanism of the inhibition, the binding of the proteins to Con A and PHA was measured. Alpha1-AGP bound well to PHA and to some extent to Con A. Alpha1-AT bound to Con A but not to PHA. Hp had a strong affinity to both and inhibited the binding of 125I-Con A to the lymphocytes. Thus, each of the proteins revealed a striking relationship between the binding capacity to lectins and the inhibitory effect on the lymphocyte transformation. This inhibitory effect of the protein seems to be mainly due to binding to the mitogens and blocking their attachment to the cells.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)