[Ascaris lumbricoides: heterogeneity in ABO epithopes expression].

Ascaris lumbricoides and its hosts can present the same ABO System epithopes. The aim was to study ABO epithopes expression in A. lumbricoides by Inhibition Agglutination Test using different monoclonal antibodies and policlonal sera. We worked with 27 parasite extracts (14 extracts from A Group patients, 2 AB Group 1, B Group and 10 from unknown ABO Group patients). Inhibition Agglutination Test was made facing the extracts from A, AB and unknown ABO Group patients against monoclonal antibodies and policlonal serum of A specificity and the extracts from B, AB and unknown ABO Group patients against monoclonal antibodies and policlonal serum of B specificity. The Semiquantitative Test was made with the extracts which inhibited the agglutination of any antibody. The 50% of the parasite extracts faced against A specificity antibodies and the 46% of the parasite extracts faced against B specificity antibodies significantly inhibited the agglutination in the Semiquantitative Test. No extract inhibited the totality of the antibodies. All the antibodies reacted with some extract, except one antibody of B specificity. The ABO activity in the extracts was independent of the antibody's immunoglobulin class, titre and concentration and it only was dependent on the antibody union with the epithope at which the antibody is directed. The heterogeneity in the ABO epithopes expression of A.lumbricoides might be involved in the escape of the host's immune response. The used Inhibition Tests are sensitive, simple, rapid and economic. We conclude that the use of different antibodies alows the best definition of the antigen-antibody specificity.