CD4(-CELLS WITH SPECIFIC REACTIVITY AGAINST ASTROVIRUS ISOLATED FROM NORMAL HUMAN SMALL-INTESTINE() T)

Background & Aims: The gut is the largest immunologic organ in the hum an body, but little is known about the antigen specificity of mucosal T cells, This study sought to determine whether T cells resident in th e duodenal mucosa could recognize astrovirus, a common and clinically important gastroenteritis virus, Serum antibodies against astrovirus a re prevalent, indicating frequent viral exposure and postinfectious in duction of systemic immune responses, Mucosal immune responses may con ceivably mediate protection on astroviral reinfections, Methods: Small intestinal biopsy specimens with normal histology were obtained from 8 adults and challenged in an organ culture system with inactivated hu man astrovirus, T cells activated by the viral challenge were isolated either by immunomagnetic positive selection of mucosal resident cells or by collecting cells emigrating into the culture supernatant, Resul ts: Astrovirus-specific, mucosal T-cell lines were isolated from all 8 subjects. Analysis of 29 CD4(+) T-cell clones from 3 subjects showed predominant HLA-DR restriction of astrovirus responses, Most of the T- cell clones showed a Th1-like cytokine profile when restimulated with astrovirus, Conclusions: Helper T cells residing in normal, duodenal m ucosa of adult subjects recognize a common enteropathogenic virus, The se mucosal CD4(+) T cells are presumably important in mucosal defense against recurrent astroviral infections.