We want to profile native human IgA antibodies with peptide microarrays (Immunocytochemistry - like application), but I can't find something that works for me for quite some time already.
In case this could help you I've used antibodies from SouthernBiotech for ELISA and they worked very well. Specifically in relation to IgA, I used the peroxidase-labeled antihuman IgA1, and it worked very well.