Ultrastructural localization of IgA globulins in normal and coeliac intestinal mucosa using immunoenzymatic methods

Using peroxidase-labelled antibodies, the ultrastructural localization of IgA immunoglobulins in duodenojejunal biopsies from children with active coeliac disease was investigated. Satisfactory penetration of conjugates was achieved by 20 hour-fixation in 4% formaldehyde and 8 hour-incubation of thick frozen sections in the presence of peroxidase-labelled anti-human alpha heavy chain antibody under continuous mild agitation. In normal duodeno-jejunal mucosa, deposits of IgA were observed at the ultrastructural level in the rough endoplasmic reticulum and the perinuclear space of plasma cells and on lateral cell membranes of villous and crypt epithelial cells. In coeliac mucosa, immuno-electron microscopic studies confirmed the increased cell density of IgA immunocytes and revealed heavy deposits of IgA on the basement membrane of surface epithelial cells and the wall of neighbouring blood vessels.