An immunocytochemical double staining technique applied to intraepithelial lymphocytes in the small intestine of the rat

To study lymphocyte antigens in cryostat sections of small intestine of the rat, an indirect double labelling technique was developed, avoiding alkaline phosphatase for the 2nd label, in view of the high endogenous activity of this enzyme in the enterocytes. 2 times a peroxidase was used, but in the 1st sequence an antibody conjugated peroxidase with a reddish brown AEC product and in the 2nd sequence an avidin conjugated peroxidase with a blue colour product via 4CN. 2 antigens on the same cell in the same section can be detected by this method. Double labelled cells were coloured violet. The method is particularly suitable for loosely situated cells.