Serum immunoglobulin levels in normal children and adults in the Lebanese and other Arab Middle Eastern populations.

Serum immunoglobulin levels were determined in 1000 serum samples of normal middle easterners. Ig levels in mothers at delivery were normal except for a depressed IgG level. In cord blood the level of IgG was higher than its level in mothers, but no IgA or IgD was found. IgD was formed in some instances in the sera of infants in the first week of life. IgG showed a pattern similar to that described by others with the lowest values at 1-2 months, increasing gradually so that by 1-3 years the normal adult blood level is reached. IgA levels continued to increase with age and although no definite explanation is available, it is interesting to speculate on the possible relationship to the increased incidence of intestinal parasitism. IgM showed significant differences between males and females being higher in the latter. IgD levels reached maximum levels by 3-5 years, and mean levels ere lower after the 14th year.