Kinetics of immunoglobulin appearance at the ocular surface

The kinetics of appearance of immunoglobulins (Ig) IgA, IgM, IgG1, and IgG2a were studied immunocytochemically at the ocular surface of Swiss-Webster mice of select ages. Immunostaining for IgA was first detectable at the corneal surface of 21 postnatal day (P) old mice. By 25 P, IgM also was present and by 30 P. IgG1 and IgG2a immunostaining was observed. No change in immunostaining was seen in one year old (365 P) animals when compared with 37 P aged mice. IgA staining was always of greater intensity than IgM, IgG1, or IgG2a. These immunocytochemical data were compared with Ig levels in pooled serum from similarly aged mice using serial radial immunodiffusion (SRID). IgA was not detected in serum until mice were 25 P; IgM at 15 P; and both IgG1 and IgG2a (presumably maternal) at 5 P. No correlation between the time of appearance of serum levels of Igs and ocular surface immunostaining was seen for any of the Igs. These studies establish the time sequence of Ig appearance at the eye surface and suggest that the source of these Igs is not the serum.