Development with age of IgA, IgG, albumin, lysozyme, and total protein in children's tears

Tears were collected on Weck cel sponges from 116 normal humans ranging in age from 1 day to 31 yr. No significant differences in the levels of any of the proteins were detected based upon race (69% blacks) or upon sex (51% male) in the 110 children in this group. The levels of IgA did not correlate with those of lysozyme, and did not correlate with the quantities of total protein. This indicates an independent mechanism of development for IgA and lysozyme. IgA and lysozyme were not detected in the children's tears at birth, i.e., < 1 mg% and < 7 mg% respectively. Within 2 wk, both had risen to levels of 2 mg% and 17 mg% respectively and adult values were attained by about 6-8 yr of age. Total protein increased significantly during the first 2 wk after birth. At birth, IgG and albumin were about 3 fold higher than adult levels and by 2-3 mth had dropped to and were maintained near adult levels, 22 and 42 mg% respectively. The quantity of albumin correlated well with that of IgG at all ages, but not with total protein, lysozyme or IgA. The high levels of IgG and albumin probably reflected a propensity for transudation from the serum of particularly the newborns which synthesize little IgG. IgA becomes the predominant immunoglobulin in tears by 6-8 mth.