Abstract
Purpose: :
Diseases of the skin can be complicated by ocular involvement that may be as distressing as the primary complaint. Any region of the eye can be involved. Melanoma patients occasionally experience a cancer–induced immune–mediated retinal degeneration; melanoma–associated retinopathy (MAR). The classic description of this syndrome includes findings of antibody activity with retinal bipolar cell components of the inner nuclear layer. However, exceptions do occur in which the melanoma patient develops a retinopathy that does not involve the inner nuclear layer. Like Cancer–Associated Retinopathy (CAR), different antigens are involved in MAR, each representing an immunologically distinct subset. This study pursues recent findings of anti–retina activity in MAR patients who share the immunologic commonality of producing antibody activity with a 20 kd retinal protein, and asks the question ’is the 20 kd reaction MAR specific, or does it occur in other types of skin cancer, or other skin diseases that are also complicated by retinal degenerations’?
Methods: :
: Western blot reactions on an extract of rhesus monkey retina, resolving patient’s antibody activity with rabbit anti–human polyvalent antibodies, conjugated to horse radish peroxidase. The antibody activity of four 20 kd reactive MAR patients was compared with that of six patient with other types of skin cancer (Squamous and Basal cell carcinomas) without ocular involvement, and four lupus patients experiencing retinal degenerations. The anatomical location of the 20 kd retinal antigen within the neurosensory retina was sought by indirect immunohistochemistry on sectioned rhesus monkey eyes
Results: :
The 20 kd retinal antigen is expressed within the photoreceptor outer segments, and extends on into the optic nerve. Two lupus patients with associated retinopathies produced antibodies reactive with this same antigen. None of the six Basal or Squamous cell skin cancer patients reacted with the 20 kd retinal antigen.
Conclusions: :
: Antibody activity with the 20 kd retinal antigen may be indicative of an autoimmune retinopathy but it is not confined to MAR patients, it is also found in other types of skin diseases in which retinal degenerations occur. These findings raise the interesting possibility that the anti–retina reaction may result from a skin disease–induced loss of tolerance to a cutaneous antigen sharing immunologic similarities with the 20 kd photoreceptor component.
Keywords: autoimmune disease • melanoma • retina: distal (photoreceptors, horizontal cells, bipolar cells)