Activation of the alternative and classical complement pathways by Entamoeba histolytica.

AUTOR(ES)

Calderon, J

RESUMO

Entamoeba histolytica HM1 supported the activation of human alternative and classical complement pathways in the absence of ameba-reactive antibodies. Nonimmune serum depleted of C1q and factor D (NHS s C1q + D) and reconstituted with C1q was able to specifically deposit C3b onto trophozoites and produce lysis. This activity was not modified by the absorption of serum on E. histolytica. Serum depleted of factor B allowed C3b binding to amebae. Serum devoid of C4 effected only small amounts of C3 uptake. The kinetics of lysis of E. histolytica by serum in the presence of Mg-EGTA [ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid] (lacking classical pathway function) or by NHS s C1q + D and reconstituted with factor D was slow and only produced one-half the amount of lysis produced by NHS s C1q + D supplemented with C1q. These results indicate that the surface of the ameba can promote complement activation by the classical pathway, without the participation of specific antibodies, and that the magnitude of this activation is greater than that induced by the alternative pathway.

Documentos Relacionados

• Inhibition of the complement membrane attack complex by the galactose-specific adhesion of Entamoeba histolytica.
• Activation of the classical and alternative pathways of complement by Treponema pallidum subsp. pallidum and Treponema vincentii.
• Attachment and ingestion of bacteria by trophozoites of Entamoeba histolytica.
• Classical and alternative complement pathway activation by pneumococci.
• Influence of serum concentration on opsonization by the classical and alternative complement pathways.