In situ hybridization as a technique for the immunological investigation of canine intestine: jejunal expression of IFN gamma and IL10 in Irish setters and beagles

In situ hybridization (ISH) has found numerous applications in biology and medicine. However, its use to demonstrate expression of cytokines within th e canine small intestine has not been described. Digoxigenin-labelled ribop robes complementary to mRNA encoding canine IFN gamma and IL10 were used to demonstrate expression of these cytokines within formalin-fixed, paraffin- embedded sections of jejunum obtained from healthy control Irish setter (IS ) dogs (n=4), gluten-sensitive IS in remission (n=7), and beagles with high enteric bacterial populations (n=5). Proportional areas of cells within th e lamina propria showing one of three mutually exclusive staining intensiti es were measured, as well as the total stained area. Intensity categories w ere chosen arbitrarily to represent cells showing weak, moderate or dense s taining (grades 1-3 respectively), reflecting increasing expression of mRNA . Control and gluten-sensitive IS showed similar total and grade-by-grade a reas of expression of IFN gamma, and IL10 in the lamina propria (p>0.05), i n contrast to beagles, which showed greater total and grade 1 areas of expr ession of IFN gamma, and greater total, grade 1 and grade 2 areas of expres sion of IL10, than both groups of IS (p<0.05). Epithelial expression of bot h cytokines was demonstrated in beagles and IS, but differences between gro ups for each cytokine were not apparent (p>0.05). This study has validated the use of in situ hybridization for the detection of IFN gamma and IL10 mR NA within canine intestinal biopsies, and has shown heightened jejunal expr ession of both cytokines in beagles with high enteric bacterial populations . (C) 1999 Elsevier Science B.V. All rights reserved.