Immunological studies on the pathogenesis of pterygium.

Immunohistochemical, electron microscopic and routine pathological studies were conducted to observe the changes in T-cell subsets, B-cells, plasma cells, and mast cells, and the distributions of immunoglobulins (IgE, IgG, IgA, IgM) and C3 in patients with pterygium. The results were as follows. Massive amounts of infiltrating lymphocytes, predominantly T-cells (CD3+), were found in the substantia propria of the pterygial specimens. The helper-suppressor ratio had risen from 1:2.7 in the normal conjunctiva to 1:1.5. Positive cytoplasmic immunoglobulin staining indicated a plasmocytic infiltration in the lesions as well. Abnormal distributions of immunoglobulins were found, and deposition of immunoglobulins in a granular pattern around the basement membrane of the epithelial layer was seen. Mast cell reactions were found, and a linear correlation between the numbers of lymphocytes and mast cells was shown. Basement membrane destruction in the cap area of the pterygium was also confirmed. These results indicate that an immunologic mechanism, possibly of Types 1, 3 and 4 hypersensitivity, may contribute to the pathogenesis of pterygium.