Serum autoantibody profiles of IgA, IgE and IgM in canine pemphigus foliaceus.

BACKGROUND

Pemphigus foliaceus (PF) is the most common IgG-mediated autoimmune skin disease in dogs. Studies of human PF have revealed the presence of other antigen-specific autoantibody isotypes, thereby uncovering new avenues of investigation of the disease pathomechanism.

HYPOTHESIS/OBJECTIVES: The aim was to obtain information about the autoantibody isotype response in canine PF.

METHODS

Sera from 34 dogs with PF were tested for the presence of antikeratinocyte, anti-desmocollin-1 and anti-desmoglein-1 IgA, IgE and IgM using indirect immunofluorescence.

RESULTS

Using our indirect immunofluorescence technique, IgA, IgE and IgM autoreactivities were detected in six, one and zero of 34 sera from PF-affected dogs, respectively. Two of the six IgA-positive sera contained antikeratinocyte and anti-desmocollin-1 IgA, while the four remaining sera tested positive either for antikeratinocyte IgA (two of six) or for anti-desmocollin-1 IgA (two of six). A single serum contained anti-desmocollin-1 IgE. None of the six sera from healthy dogs contained detectable IgA, IgE or IgM autoantibodies.

CONCLUSIONS AND CLINICAL IMPORTANCE

Our findings suggest that sera from dogs with PF rarely contain IgA or IgE autoantibodies at levels detectable by indirect immunofluorescence, while IgM autoreactivity appears not to be a feature of this disease. Considering these findings, it appears that canine PF is aetiologically and immunologically similar to that of the classic human PF, in which the IgG autoantibody response is also the predominant type.