The fate of antigen-antibody complexes in the rabbit cornea

The mechanisms involved in the clearance of immune deposits in tissues are not yet clear. The cornea was chosen as a model to examine this question due to its avascularity and transparency. Bovine serum albumin (BSA) and rabbit anti BSA serum were injected at opposite sites into the corneal stroma of unsensitized rabbits. Within a day, a sharp opaque line was seen macroscopically between the two injection sites. Sections of the corneas were examined by light microscopy and electron microscopy; furthermore, immunohistochemical techniques were used. With the light microscope, a precipitation line was seen in the corneal stroma, which was identified as an antigen-antibody complex by immunofluorescence techniques. In the same area infiltrating polymorphonuclear cells and swollen keratocytes were observed. In the ultrathin sections precipitates were seen lying between the collagen fibrils without affecting the structure of the collagen. The swollen keratocytes had an activated rough endoplasmic reticulum. In certain cases the precipitates appeared to be intracellular, both in the polymorphonuclear cells, as well as in the keratocytes. These findings suggest that stromal keratocytes may play an important role in the degradation of corneal immune deposits.