Laminin detection in normal and retinitis pigmentosa human retina.

Epiretinal membrane formation in the posterior pole is an almost constant feature of eyes with retinitis pigmentosa. Using a modified direct immunofluorescence reaction, we demonstrated a strong reaction with antilaminin in a band-like pattern on the inner retinal surface of 3 eyes with retinitis pigmentosa. There were also strongly-laminin-positive pigmented and unpigmented cells scattered throughout the degenerated retinas. This pattern was in sharp contrast to that seen in normal retinas, where the linear band of reaction at the internal limiting membrane was faint and accompanied by a zone of reaction at the level of the outer limiting membrane. Quantitation of laminin by ELISA revealed a six- to ten-fold increase (per mg protein) in retinitis pigmentosa retinas, as compared with normal. Since both glial and retinal pigmented epithelial cells can synthesize and deposit laminin, both may participate in the gliosis that occurs during the course of retinitis pigmentosa.