Human T- and B-cell responses to Schistosoma mansoni recombinant glyceraldehyde 3-phosphate dehydrogenase correlate with resistance to reinfection with S. mansoni or Schistosoma haematobium after chemotherapy.

Recently we reported that human T- and B-cell recognition of a 42-kDa protein (p42) in soluble extracts of adult Schistosoma mansoni worms correlates with resistance to reinfection with S. mansoni or S. haematobium. Amino acid microsequencing of p42 revealed that it consists predominantly of schistosome glyceraldehyde 3-phosphate dehydrogenase (SG3PDH). We have expressed SG3PDH in Escherichia coli and purified the recombinant protein in a soluble and enzymatically active form. Recombinant SG3PDH (rSG3PDH) reacted with human monospecific antibodies to p42. Lymphoproliferation and production of interleukin-4 and gamma interferon (IFN-gamma) after in vitro stimulation with rSG3PDH and serum isotype responses to rSG3PDH were examined in individuals with extremes of resistance and susceptibility to reinfection after treatment of previous S. mansoni or S. haematobium infection. Lymphoproliferation and IFN-gamma production in response to rSG3PDH and the presence of serum immunoglobulin G1 (IgG1), IgG3, and IgA antibodies to rSG3PDH generally characterized individuals who are resistant to reinfection after chemotherapy. The data indicate that T- and B-cell immune reactivity to rSG3PDH correlates with resistance to reinfection, confirming previous studies identifying SG3PDH as a target of protective immunity in humans, and suggest that SG3PDH should be investigated as a possible vaccine for human schistosomiasis.

Is the coagulopathy of hepatosplenic schistosomiasis immune-related?

Some of the soluble factors that affect haemostasis produced in the course of hepatosplenic schistosomiasis, including endotoxins (Ex), interleukin-1 alpha (IL-1 alpha) and tumour necrosis factor-alpha (TNF-alpha) were studied. Forty-one patients with hepatosplenic schistosomiasis were studied and classified into early hepatosplenic schistosomiasis (n = 12), hepatocellular decompensation (n = 14), vascular decompensation (n = 15) as well as twelve healthy controls. Thrombin-antithrombin complex (TAT), protein C and free protein S antigen and activity, endotoxin, IL-1 alpha and TNF-alpha levels were measured in all cases. Evidence of enhanced thrombin generation (elevated TAT levels) with reduced anticoagulant potential (reduced protein C and free protein S antigen and activity levels) could be demonstrated, thus reflecting decreased production and increased consumption of both coagulant and anticoagulant proteins. The association of high Ex, IL-1 alpha and TNF-alpha levels may suggest their possible implication in the causation of intravascular coagulation in hepatosplenic schistosomiasis.