B lymphocyte intestinal homing in inflammatory bowel disease.
BACKGROUND
Inflammatory bowel disease (IBD) is thought to be due to an abnormal interaction between the host immune system and commensal microflora. Within the intestinal immune system, B cells produce physiologically natural antibodies but pathologically atypical anti-neutrophil antibodies (xANCAs) are frequently observed in patients with IBD. The objective is to investigate the localisation of immunoglobulin-producing cells (IPCs) in samples of inflamed intestinal tissue taken from patients with IBD, and their possible relationship with clinical features.


METHODS
The IPCs in small intestinal, colonic and rectal biopsy specimens of patients with IBD were analysed by means of immunofluorescence using polyclonal rabbit anti-human Ig and goat anti-human IgM. The B cell phenotype of the IPC-positive samples was assessed using monoclonal antibodies specific for CD79, CD20, CD23, CD21, CD5, λ and κ chains. Statistical correlations were sought between the histological findings and clinical expression.


RESULTS
The study involved 96 patients (64 with ulcerative colitis and 32 with Crohn's disease). Two different patterns of B lymphocyte infiltrates were found in the intestinal tissue: one was characterised by a strong to moderate stromal localisation of small IgM+/CD79+/CD20-/CD21-/CD23-/CD5± IPCs (42.7% of cases); in the other (57.3%) no such small IPCs were detected in stromal or epithelial tissues. IPCs were significantly less frequent in the patients with Crohn's disease than in those with ulcerative colitis (p = 0.004).


CONCLUSIONS
Our findings suggest that different immunopathogenetic pathways underlie chronic intestinal inflammation with different clinical expressions. The presence of small B lymphocytes resembling B-1 cells also seemed to be negatively associated with Crohn's disease. It can therefore be inferred that the gut contains an alternative population of B cells that have a regulatory function.
Laboratory Unit, Fatebenefratelli Hospital, Milan, Italy. caterina.defendenti@fbf.milano.it
Caterina
C
Defendenti
Piercarlo
P
Sarzi-Puttini
Silvia
S
Grosso
Annamaria
A
Croce
Olivia
O
Senesi
Simone
S
Saibeni
Simona
S
Bollani
Piero Luigi
PL
Almasio
Savino
S
Bruno
Fabiola
F
Atzeni
D000328:Adult; D000368:Aged; D015703:Antigens, CD / Q000378:metabolism; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D001706:Biopsy; D002454:Cell Differentiation; D002465:Cell Movement; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D007075:Immunoglobulin M / Q000378:metabolism; D056747:Immunomodulation; D016130:Immunophenotyping; D015212:Inflammatory Bowel Diseases / Q000276:immunology* / Q000473:pathology / Q000503:physiopathology; D007413:Intestinal Mucosa / Q000473:pathology*; D007422:Intestines / Q000473:pathology*; D008297:Male; D008875:Middle Aged
D015703:Antigens, CD; D007075:Immunoglobulin M