Class switch and IgE production in germinal centers of intestinal tissues from patients with food allergy

GUZMAN LUCIANA; ALTAMIRANO MARÍA EUGENIA; DOCENA GUILLERMO H.; PUCCI MOLINERIS MELISA; GONZALEZ VILLAR M TERESA; MUGLIA CECILIA; CANZIANI KARINA; BERNEDO VIVIANA; GARCIA MARCELA

MAR DEL PLATA

Congreso; Congreso anual de la Sociedad Argentina de Inmunología, en el marco del congreso conjunto SAIC-SAI-SAFIS; 2018

IgE is known as a key mediator of allergic responses; however the production of this antibody has remained largely unknown in patients with food allergy. The intestinal tissue has been proposed as a potential site for production. We have previously reported that patients with juvenile polyps (JP) and high levels of serum IgE, showed an inflammatory cell infiltrate with a Th2-biased and a large number of IgE-producing plasma cells in the gut. The presence of a secondary lymphoid organ-like histology in the stroma of the polyp tissue (PT) prompted us to study the presence of germinal centers (GC) and the local production of IgE antibodies. PT and surrounding mucosa (SCT) biopsies from patients with rectal bleeding (n=7) were studied by histology, confocal microscopy and RT-qPCR; cytokines were assessed by CBA and ELISA; germinal centers were isolated by laser dissection microscopy (LDM) and analyzed by PCR. We found germinal center-like cell agglomerates containing CD20+, Ki67+ and AID+ B cells and CD57+ mononuclear cells (follicular helper T cells). We also observed a high frequency of IgE+CD138+ plasma cells (91.25±6.71% of IgE+CD138+ cells of total plasma cells) in the marginal region of germinal centers. SCT showed the absence of these cells. PCR was assessed in RNA isolated from the removed GC with specific primers for different isotype class switch intermediates (sterile and circle transcripts) and we found bands corresponding to direct (μ to ε) and sequential class switch (μ to γ and γ to ε).In conclusion, our findings showed that IgE is produced at the mucosa and the local Th2 environment may be strongly linked to the presence of active germinal centers that generated IgE. Likewise, this work provides the first evidence that class switch recombination to IgE occurs in the colonic mucosa of patients with food allergy.