An ELISA method to measure total and specific human secretory IgA subclasses based on selective degradation by IgA1-protease.
We have taken advantage of the property of IgA1-proteases to selectively cleave the human IgA1 subclass into Fabalpha and Fcalpha-J chain-secretory component (Fcalpha-J-SC) fragments in order to design a novel ELISA method for measuring the two secretory IgA (S-IgA) subclasses in secretions. The assay is based on the loss of detection of S-IgA1 by a combination of peroxidase-labelled antibodies to secretory component and Fab following IgA1-protease treatment. The specificity is that of the protease and the sensitivity of the detection is 5 ng/ml. Moreover, the use of purified S-IgA1 and S-IgA2 controls is not necessary. The assay has been successfully applied to the analysis of colostral S-IgA antibodies (Abs) to HIV-1-gp160 from HIV-1 positive women. The major subclass of colostral S-IgA antibodies to gp160 was found to be of the alpha1 isotype but the specific activity of anti-HIV-gp160 S-IgA2 was, however, higher than that of S-IgA1.
Hocini
H
H
Unité INSERM U430, Hôpital Broussais, 96 rue Didot 75674, Cedex 14, Paris, France. hakim.hocini@brs.ap-hop-paris.fr
Iscaki
S
S
Bouvet
J P
JP
Kazatchkine
M D
MD
Bélec
L
L
D000328:Adult; D000918:Antibody Specificity; D003126:Colostrum / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D015483:HIV Antibodies / Q000302:isolation & purification; D019302:HIV Envelope Protein gp160 / Q000276:immunology; D006679:HIV Seropositivity / Q000276:immunology; D015497:HIV-1 / Q000276:immunology; D006801:Humans; D007071:Immunoglobulin A, Secretory / Q000032:analysis*; D012463:Saliva / Q000276:immunology; D012697:Serine Endopeptidases / Q000378:metabolism*; D013379:Substrate Specificity
D015483:HIV Antibodies; D019302:HIV Envelope Protein gp160; D007071:Immunoglobulin A, Secretory; D012697:Serine Endopeptidases; C021433:IgA-specific serine endopeptidase