CLDN1 and Autoimmunity: Also, Paneth cells (PCs) as the only cells of the immune periphery with an active Defa6 promoter (the driver of OVA in OVA+Cldn1+/+ and OVA+Cldn1−/− chimeras) showed similar numbers in the ileum of all BM chimeras (Fig. S5, E and F), further supporting the negligible role of OTIIs in the observed autoimmunity.