Dissociation of immunoregulatory function of blood monocytes from maturational state and expression of interleukin-1 in humans chronically infected with Schistosoma mansoni

We investigated the immunoregulatory function and properties of monocytes in 54 S. mansoni infected Egyptians (40-3,840 S. mansoni eggs excreted per gram of stool) 13-35 years of age. Adherent cell-mediated suppression was found in 11 of 36 patients. Cytochemical studies and reactivity with monoclonal antibodies directed at differentiation markers failed to show alterations in the distribution or maturation of monocytes. Peripheral blood mononuclear cells (PBMC) from these individuals produced lower levels of interleukin-1 (IL-1) in response to bacterial lipopolysaccharide and Staphylococcus albus stimulation as compared to the other S. mansoni infected individuals. Overall, IL-1 production by PBMC stimulated with LPS or Staphylococcus albus was higher in infected individuals compared to uninfected controls and correlated with intensity of infection (r = 0.41, P = 0.002 for LPS; r = 0.45, P = 0.006 for S. albus). IL-1 expression by monocytes from individuals with heavy S. mansoni infection exceeded that of subjects with light infection. The intensity-related increase in IL-1 expression did not correlate with the maturational state or the immunoregulatory properties of the monocytes.