Gluten Stimulation of Coeliac Mucosa In Vitro Induces Activation (CD25) of Lamina Propria CD4H T cells and Macrophages but no Crypt‐Cell Hyperplasia

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Abstract
Jejunal biopsy specimens from 10 patients with treated coeliac disease and seven non-coeliac controls were challenged in vitro with peptic-tryptic gluten digest. Mucosal T cells were examined in situ by three-colour immunofluorescence staining for expression of the activation marker CD25 (the p55 α-chain of intcrlcukin-2 receptor) and the nuclear proliferation marker revealed by monoclonal antibody Ki-67. Intraepithelial T cells expressed CD25 rarely whereas the proportion of activated lamina propria T cells increased (P< 0.002) from median 2.8% (cultured with 20% fetal calf serum alone for 24–48 h) to 10.0% after 24h with gluten (n= 10; range 1.1–17.4%) and to 10.4% after 48 h (n = 7; range 1.4–17.5%). Such gluten-induced increase of CD25+ T cells was not observed in specimens from non-coeliac control subjects. Crypt-cell hyperplasia and T-cell proliferation (Ki-67+) were observed neither in the coeliac nor in the control mucosae after gluten stimulation. Three-colour staining combining a polyclonal antibody reagent to CD3 and a monoclonal antibody to CD25 with a monoclonal antibody to CD45RO, CD4. CDS, the p75 β-chain of intcrleukin-2 receptor, integrin χEβ7, or HLA-DR showed that most of the CD25+ T cells (> 90%) were CD4+ CDS, co-expressed CD45RO and the p75 β-chain. and often also the integrin χEβ7 but not HLA–DR. In addition to these activated T cells, a dominating population of CD25+ CD3-CD4+ subepithelial pan-HLA–class I+ macrophages (CD68+) with variable expression of the p75 β-chain was often induced by gluten challenge.