Morphology of delayed-type hypersensitivity reactions in the guinea pig cornea

Guinea pigs sensitized with several soluble protein antigens in incomplete Freund's adjuvant (IFA) and tested at 5 to 7 days developed basophil-rich corneal reactions characterized by minimal edema and fibrin deposition. These lesions resembled the skin reactions of cutaneous basophil hypersensitivity (CBH) in their immunization requirements, time course, and character, but differed in that basophils were relatively less frequent and eosinophils and neutrophils more numerous in ocular than in cutaneous reactions developing simultaneously in the same animal. In contrast, animals immunized with antigens such as ovalbumin in complete Freund's adjuvant (CFA) developed much more severe delayed-type ocular reactions whether tested at early or late intervals after sensitization. These intensely injected, chemotic reactions exhibited an extensive cellular infiltrate of mononuclear cells as well as marked corneal edema accompanied by extensive fibrin deposition. Hence, these ocular reactions were similar to the classic indurated tuberculin-type delayed hypersensitivity (DH) skin reactions except that neutrophils were more numerous. These data indicate that in the eye as in the skin two distinct patterns of delayed-onset, cell-mediated hypersensitivity may occur to the same antigen, depending on the mode of immunization and the time of testing. However, significant differences were found in the frequency with which the various granulocytes infiltrated reactions elicited simultaneously in the eye and skin. Therefore, the character of immune expression may vary in different parts of the body and local factors, such as the local microvasculature, evidently contribute to these differences.