Immunocytochemical localization of immunoglobulins at the corneal surface of the mouse.

Immunoglobulins A, G1, G2a and M were localized at the corneal surface of adult Swiss-Webster mice using Sternberger's peroxidase anti-peroxidase (PAP) technique. Immunoglobulins G2b, G3 and E and lysozyme were not present at the corneal surface of the mouse. Light microscopy of whole mouse eyes incubated for the detection of immunoglobulin A (IgA) demonstrated a population of positively-stained corneal surface cells. IgG1, IgG2a and IgM could not be similarly detected at the light microscopic level. At the transmission electron microscopic level, a greater amount of staining for IgA was localized over the mature corneal surface cells. A lesser amount of IgA staining occurred over the young and mature corneal surface cells. In contrast to this, IgG1, IgG2a and IgM were randomly distributed over the corneal surface and were not preferentially localized over young or mature surface cells. The staining for IgG1, IgG2a and IgM was less than the staining for IgA at the corneal surface. IgA was also localized at the corneal surface using an indirect immunoferritin technique. These studies suggest that immunoglobulins A, G and M are intimately associated with the glycocalyx and microvilli of the corneal surface cells. At present it is not known whether these immunoglobulins are bound directly to the surface cell apical plasma membrane or indirectly via mucus glycoproteins at the ocular surface.