Phenotype of exogenous microparticle-containing pigment cells of the human Peyer's patch in inflamed and normal ileum.

OBJECTIVES: Pigmented cells, that contain inert, submicron-sized dietary particles, are a consistent feature of the base of human Peyer's patches (PP). We aimed (i) to phenotype these intestinal pigment cells (PC) in archival tissue specimens and (ii) to establish whether PC phenotype is altered in inflammatory conditions, especially Crohn's disease (CD). METHODS: PCs contained within PP were identified by routine haematoxylin and eosin (H&E) staining and dark field microscopy of archival ileal sections for: adenocarcinoma (n=16), colonic CD (n=23), non-CD colitis (n=10). Paraffin-embedded serial sections were graded for microscopic inflammation and then investigated immunohistochemically with antibodies against CD68, MAC387, CD14, CD11b, CD15, CD1a, S100, HLA-DR, CD86 and Cathepsin D. Analyses were by light and confocal microscopies. RESULTS: The majority of PCs were CD68 positive (circa 80%) with a minority (circa 20%) staining for MAC387. Microparticles were mainly identified within cathepsin D negative lysosomal compartments. Histological inflammatory grade and disease type had no influence on cell phenotype. CONCLUSIONS: The microparticle-containing PCs of the PP base are mainly mature macrophages (CD68) of low metabolic and immunological activity. There is no evidence of differential PC phenotype or activation in differing disease states, including CD.

Peripheral blood mononuclear cell proliferative responses to soluble and particulate heat shock protein 65 in health and inflammatory bowel disease.

OBJECTIVES: The aims of this study were to determine, in peripheral blood mononuclear cells (PBMC), whether particulate antigen triggers (i) an amplified cell proliferative response compared to soluble antigen and (ii) a dysfunctional response in cells derived from patients with chronic inflammation and specifically in those with inflammatory bowel disease (IBD). SUBJECTS: Healthy volunteers (n = 17), inflammatory controls (n = 8) and patients with IBD (n = 17) were recruited from St Thomas' and Guys' Hospital, London, UK. METHODS: Following optimisation of experimental conditions (0.1-10.0 mug/ml antigen), PBMC were stimulated with (i) 10.0 mug/ml recombinant soluble heat shock protein 65 (hsp 65) and (ii) 1.0 and 10.0 mug/ml hsp 65 conjugated to microparticles (0.5 mum diameter). PBMC proliferative responses were measured by (3)H-Thymidine incorporation at day 5 and results compared between groups using unpaired t-test. RESULTS: Conjugation to microparticles of low dose hsp 65 significantly increased overall proliferative responses by 2-11 fold compared to soluble antigen alone (p < 0.05). However, no specific PBMC proliferative dysregulation was noted in cells from subjects with IBD. CONCLUSIONS: Low dose antigen, in microparticulate form, leads to amplified cell proliferation in primary human cells, as showed previously in cell lines and animal studies. However there is no abnormal proliferative response in cells from subjects with IBD.