MICA is expressed in CD7+ and CD138+ cells in human small intestinal mucosa

ALLEGRETTI Y; GUZMAN L; CUETO RUA E; DRUT R; ZWIRNER N; CHIRDO, FG

Rio de Janeiro, Brasil

Congreso; XIII International Congress of Immunology; 2007

IUIS

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-GB;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> MICA (MHC class I chain related A) is a non classical MHC class I polymorphic protein, involved in immunosurveillance mechanisms. MICA is expressed at low levels in enterocytes, but it is upregulated by cellular distress. Previous observations from our group showed that, in addition to the enterocyte, MICA is expressed in other cells in the intestinal mucosa. The aim of this study was to identify the lineage of MICA+ cells from the intraepithelial (IE) and lamina propria (LP) compartments, in biopsy specimens from paediatric patients with normal histology, inflammatory signs or villus atrophy. Immunofluorescence analysis by confocal microscopy showed that MICA was commonly present in the perinuclear region of the enterocytes: Its expression was very low in normal intestine, but it was upregulated in mild and severe enteropathy. In samples with normal histology, MICA was observed in 8% of the CD7+ cells in the IE compartment but not in CD57+ cells. In LP, 3% of the CD7+ and 60% of the CD138+ (plasma cells) were MICA+. In severe enteropathy, 2% of CD7+ IE cells, 2% of CD7+, and 50% of the CD138+ LP cells were MICA+. Absolute number of these populations was increased in enteropathy. MICA staining was much more intense in CD7+ and CD138+ cells than in enterocytes. Other MICA+ cells remain to be identified. In conclusion, some of the CD7+ and CD138+ cells present in the intestinal mucosa expressed MICA. The number of MICA+ cells was increased in both IE and LP compartments in mild and severe enteropathy.