HUMORAL AND MUCOSAL IGA ANTIBODY-RESPONSE TO A RECOMBINANT 52-KDA CYSTEINE-RICH PORTION OF THE ENTAMOEBA-HISTOLYTICA GALACTOSE-INHIBITABLE LECTIN CORRELATES WITH DETECTION OF NATIVE 170-KDA LECTIN ANTIGEN IN SERUM OF PATIENTS WITH AMEBIC-COLITIS

Humoral and mucosal IgA responses to a recombinant cysteine-rich porti on (designated LC3) of the Entamoeba histolytica galactose-inhibitable lectin's 170-kDa subunit were determined in patients with amebic coli tis. All patients had 170-kDa amebic antigen in serum, compared with 1 of 50 cyst passers and 1 of 31 controls (P <.01). Seven days after tr eatment, serum and fecal 170-kDa antigen became undetectable in 12 of the 13 patients (P <.001). Serum anti-LC3 IgA was found in 83.8% of co litis patients, compared with 2% of controls and 12% of asymptomatic c yst passers (P <.001). Salivary and fecal anti-LC3 IgA levels were hig her in patients than in cyst passers (P <.001). In conclusion, in ameb ic colitis, development of humoral and mucosal IgA responses to the re combinant LC3-encoded protein correlates with detection of amebic 170- kDa antigen in serum and feces.