Entamoeba lectin epitopes recognized by human IgA antibodies identified.

2004 SEP 1 - (NewsRx.com & NewsRx.net) -- Researchers have identified the Entamoeba histolytica galactose-inhibitable lectin epitopes recognized by human immunoglobulin A antibodies following cure of amebic liver abscess.

"Immunity to Entamoeba species intestinal infection is associated with the presence of intestinal IgA antibodies against the parasite's galactose-inhibitable adherence lectin. We determined the epitope specificity of serum and intestinal antilectin IgA antibodies by enzyme-linked immunosorbent assay using overlapping fragments of a recombinant portion of the lectin heavy subunit, designated LC3. These findings were correlated with the effects of epitope-specific murine antilectin immunoglobulin A (IgA) monoclonal antibodies (MAbs) on amebic in vitro galactose-specific adherence," scientists in the United States and South Africa report.

"LC3 is a highly antigenic and immunogenic cysteine-rich protein (amino acids [aa] 758 to 1150) that includes the lectin's carbohydrate binding domain," said Mohamed D. Abd-Alla at the University of Minnesota and collaborators in the U.S. and South Africa. "The study subjects, from Durban, South Africa, were recently cured of amebic liver abscess (ALA) with or without concurrent Entamoeba histolytica intestinal infection or were infection free 1 year after cure. We also studied seropositive subjects that were infected with E. histolytica, disease-free, and asymptomatic."

"Serum anti-LC3 IgA antibodies from all study groups exclusively recognized the third (aa 868 to 944) and the seventh (aa 1114 to 1134) LC3 epitopes regardless of clinical status; epitope 6 (aa 1070 to 1114) was also recognized by serum anti-LC3 IgG antibodies," reported Abd-Alla and his colleagues. "However, IgG antibody recognition of epitope 6 but not 3 or 7 was lost 1 year following cure of ALA. We produced 14 murine anti-LC3 IgA MAbs that collectively recognized five of ...