ABSTRACT
Recent studies have shown that the the nervous system possesses immunoregulatory function. We investigated the effect of substance P(SP) a neuropeptide on the expression of HLA-DR and HLA-DQ antigens on normal human monocytcs of the peripheral blood. APAAP (alkaline phosphatase-antialkalinc phosphatasc) enzyme immunoassay was adopted to detect the HLA class Ⅱ molccults, using monoclonal antibodies Tu36, Tu22, in the reaction system. The results, showed that SP at concentrations higher than the physiological serum level (10~(-10)mol/L, 30~(-8)mol/L, 10~(-6)mol/L) promoted the expression of HLA-DQ antigen on monocytcs significantly in vitro (P0.05). The maximal effect was observed at 10~(-8)mol/L. Expression of HLA-DR antigen, however, was not influenced by SP in the same range of SP concentrations. It is reasoned by the authors that the immunosupprcssivc effect of excessive glucocorricoids during stress might partly be counterbalanced by the uprcgulatory action of increased blood SP on the immune function.