Schistosoma mansoni antigenic preparations interfere with normal human polymorphonuclear leukocyte function

ABSTRACT

The aim of this study was to examine the effects of various forms of Schistosoma mansoni antigens, namely, schistosomulae, soluble egg antigens [SEA] and soluble worm antigenic preparation [SWAP], on the oxidative burst and phagocytosis by normal human polymorphonuclear leukocytes [PMNs]. The PMNs were stimulated with phorbol myristate acetate [PMA] or opsonized yeast [OPY]. Incubation of schistosomulae [10-100] with whole blood or PMNs significantly depressed the oxidative burst of stimulated PMNs as measured by chemiluminescence [CL] technique. Addition of various concentrations of SEA to PMNs directly inhibited phagocytosis of yeast and PMNs-CL response in a time- and concentration-dependent manner. In contrast, SWAP failed to exert any significant inhibition. The inhibitory effect of SEA was shown to be reversible and heat sensitive. Furthermore, schistosoma antigens did not produce a cytotoxic effect on PMNs as determined by the trypan blue exclusion test. The incubation of oxygen scavengers such as superoxide dismutase [SOD] dimethyl sulphoxide [DMS] and catalase with SEA potentiated its inhibitory effect on PMNs-CL. In conclusion, there was a significant inhibition of oxidative burst and phagocytosis by SEA suggesting that a similar effect may occur on PMNs during S. mansoni infection in humans