Letter regarding “ACVIM consensus statement on pancreatitis in cats”
I am writing with a comment on a statement in the ACVIM consensus statement on pancreatitis in cats.1 I realize this statement was published nearly 3 years ago. However, I thought the point was important enough to justify the letter in case it is of help to future researchers investigating pancreatitis in cats.
Autoimmune pancreatitis (AIP) occurs uncommonly in people. It can be categorized as type 1 when the pancreas is involved in a multisystemic fibro-inflammatory disease (also known as immunoglobulin 4 [IgG-4]-associated systemic disease) and as type 2, which has been associated with chronic enteropathy.21 The presence of IgG4-staining cells in the pancreas and incidence of circulating antibodies against the pancreas have not been established in cats, but response to immunosuppressive therapy with chronic pancreatitis may suggest an immune-mediated etiology in some cats.
I agree with the consensus group that it is likely that some cats may suffer from a form of autoimmune pancreatitis. However, I would like to stress that research already undertaken has shown that, unlike dogs and humans, cats do not produce an immunoglobulin subclass equivalent to human IgG4. Strietzel and others reported a rapid amplification of circular DNA (RACE) and full-length PCR study of feline IgG subtypes.2 Before their study, only 2 feline IgG subtypes were recognized, which appeared to have functionality equivalent to human IgG1 and thus were named feline IgG1a and 1b. Strietzel et al also identified these IgG1 alleles but, in addition, they found a third subtype of IgG in cats which they named IgG2, because its functional characteristics were similar to IgG2 in humans. They stressed that neither this IgG nor the previously described IgG1 subtypes had functional characteristics similar to human IgG4.
Further investigations into the etiology of chronic pancreatitis in cats are very much needed. However, studies pursuing IgG4-related disease in this species by looking for the presence of tissue-specific IgG4-staining plasma cells, as our group found in dogs,3 or searching for circulating IgG4 in cats would seem futile.
Yours faithfully,
Penny Watson
