Findings from a study in 2011 reveal that it is possible to be sensitive to gluten and not have Celiac Disease. While Celiac Disease (CD) affects 1% of the US population, the Center for Celiac Research estimates that gluten sensitivity (GS) may affect 6% of the population. Although results are preliminary, GS appears to be less clinically severe than CD. Symptoms of GS primarily affect the gastrointestinal system but they are not mediated (caused) by the immune system. As evidenced by several human intestinal biopsies, GS did not appear to cause damage to intestinal tissue as typically seen in CD. Small amounts of gluten may be tolerable in gluten sensitive persons, unlike that of CD, though ultimately both conditions benefit from a gluten-free diet.
Reference: Sapone et al. Divergence of gut permeability and mucosal immune gene expression in two gluten-associated conditions: Celiac Disease and gluten sensitivity. BMC Medicine. 2011. 9(23). http://www.biomedcentral.com/1741-7015/9/23