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Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
ISSN: 1678-8060
EISSN: 1678-8060
Vol. 90, No. 2, 1995, pp. 289-292
Bioline Code: oc95057
Full paper language: English
Document type: Research Article
Document available free of charge

Memórias do Instituto Oswaldo Cruz, Vol. 90, No. 2, 1995, pp. 289-292

 en Novel Mechanisms of Immune Evasion by Schistosoma mansoni
Zvi Fishelson

Abstract

The interaction of  Schistosoma  mansoni
  check for this species in other resources
 with its host's
immune system is largely affected by multiple specific and 
non-specific evasion mechanisms employed by the
parasite to reduce the host's immune reactivity. Only little
is known about these mechanisms on the molecular level. The four 
molecules described below are intrinsic parasitic proteins recently 
identified and studied in our laboratory.

1. m28 - A 28kDa membrane serine protease. m28 cleaves iC3b and can thus restrict attack by effector cells utilizing complement receptors (especially CR3).
Treatment with protease inhibitors potentiates killing of schistosomula by complement plus neutrophils.

2. Smpi56 - A 56kDa serine protease inhibitor. Smpi56 binds covalently to m28 and to neutrophil's elastase and blocks their proteolytic activity.

3. P70 - A 70kDa C3b binding protein. The postulated activity of P70 includes binding to C3b and blocking of complement activation at the C3 step.

4. SCIP-1 - A 94kDa schistosome complement inhibitor. SCIP-1 shows antigenic and functional similarities to the human 18kDa complement inhibitor CD59. Like CD59, SCIP-1 binds to C8 and C9 and blocks formation of the complement membrane attack complex. Antibodies directed to human CD59 bind to schistosomula and potentiate their killing by complement.

The structure and function of these four proteins as well as their capacity to induce protection from infection with S. mansoni are under investigation.

Keywords
immune evasion - complement - protease - inhibitor - CD59

 
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