title: Autoimmune pancreatitis: frequency, IgG4 expression, and clonality of T and B cells.
abstract: Autoimmune pancreatitis (AIP) is a newly recognized disease. The presence of IgG4 positive plasma cells is thought to be of diagnostic help. In a surgical series of chronic pancreatitis cases, we determined the relative frequency of AIP before and after 1990, analyzed the diagnostic significance of IgG4 expression and examined the presence of oligoclonal T or B-cell populations. The histopathology of 202 surgical specimens of chronic pancreatitis removed between 1975 and 2004 was reviewed and 2 groups were distinguished, 1 of AIP cases and the other of nonautoimmune chronic pancreatitis (non-AIP CP). The intensity of infiltration of pancreatic tissue by IgG4 positive plasma cells and other immune cells was studied immunohistochemically. Finally, T and B-cell clonality was tested by polymerase chain reaction-based analysis. Except for 1 case in 1978, all cases of AIP were observed after 1990. IgG4 positive plasma cells were detected in 72.5% of AIP cases and in 63.1% of non-AIP CP cases. More than 20 cells per high power field were only seen in AIP (sensitivity 43%, specificity 100%). This finding was associated with higher age and grade. Polyclonal T and B-cell populations were found in both AIP and non-AIP CP except for 1 AIP case showing an oligoclonal IgGH-FR3 gene rearrangement. AIP seems to have increased considerably in frequency in the last 2 decades. High density infiltrates of IgG4 positive plasma cells are diagnostic for AIP, but are seen in less than half of the cases. T or B-cell oligoclonality could not be established as a feature of AIP.
authors.affiliation: Department of Pathology, University of Kiel, Germany.
authors.forename: Motohiro
authors.initials: M
authors.lastname: Kojima
authors.forename: Bence
authors.initials: B
authors.lastname: Sipos
authors.forename: Wolfram
authors.initials: W
authors.lastname: Klapper
authors.forename: Olaf
authors.initials: O
authors.lastname: Frahm
authors.forename: Hans-Christian
authors.initials: HC
authors.lastname: Knuth
authors.forename: Akio
authors.initials: A
authors.lastname: Yanagisawa
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Zamboni
authors.forename: Toshio
authors.initials: T
authors.lastname: Morohoshi
authors.forename: Günter
authors.initials: G
authors.lastname: Klöppel
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001327:Autoimmune Diseases / Q000175:diagnosis / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D002999:Clone Cells; D005260:Female; D015326:Gene Rearrangement, B-Lymphocyte, Heavy Chain; D006801:Humans; D007074:Immunoglobulin G / Q000096:biosynthesis*; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D050500:Pancreatitis, Chronic / Q000175:diagnosis / Q000453:epidemiology / Q000276:immunology*; D016692:Receptors, Antigen, T-Cell, gamma-delta; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D007074:Immunoglobulin G; D016692:Receptors, Antigen, T-Cell, gamma-delta