Immunolocalization of integrins in the human retina

Purpose. Integrins are cell surface proteins that participate in interactions between cells and with extracellular matrix. Binding of integrins to their ligands influences cell activities including proliferation, migration, and differentiation. Expression of integrin subunits from three different subfamilies was examined in human retina. Methods. Integrins were detected in frozen sections of two human retinas with an avidin-biotin-complex immunohistochemical technique, using nine different monoclonal antibodies specific for α₂, α₃, α₄, α₅, α₆, α(v), β₁, β₂, and β₃. One retina was from a patient who had conjunctival squamous cell carcinoma, and the other was from uninvolved regions of an eye with a choroidal melanoma. Results. All integrins tested were detectable in consistent patterns in two retinas. All except α₂ and α₄ were stained vibrantly in retinal and choroidal vessels. All alpha subunit staining of vessels showed overlap or close proximity to β₁ staining. In addition to vessels, β₁ was also present in the internal limiting membrane; α₂, α₃, α₄, α₅, and β₂ were all found throughout much of the neural retina, albeit with distinctive staining patterns. Other than in association with vessels, α₆ and α(v) were not detected in neural retina, and β₃ was only weakly detected in the nerve fiber layer; α₄ and β₂ were expressed in the retinal pigment epithelium; β₁ and β₂ were strongly expressed in drusen present in one of the eyes. Conclusion. Nine integrin subunits have been found to have unique distributions in adult human retina. An understanding of the distribution in normal retina can serve as a useful contrast to patterns of staining associated with retinal diseases.