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The total kappa/lambda immunoglobulin light chain ratio and the kappa/lambda ratios within each of the serum immunoglobulin classes G, A, and M were measured in thirteen patients with humoral immunological disorders. Of those patients, eight had common variable immunodeficiency whereas five patients had other forms of humoral immunological deficiencies. Eleven patients had abnormal antibody response in vivo. All but three of the thirteen patients had clearly abnormal light chain ratios in one or more of the immunoglobulin classes. We conclude that humoral immunological disorders, usually characterized by abnormal heavy chain production and a disturbed antibody response, may frequently have a concomitant abnormal synthesis of the light chains resulting in an abnormal kappa/lambda light chain ratio.

Values for the kappa/lambda light chain ratio in immunoglobulins G, A and M and the total kappa/lambda ratio, measured by enzyme linked immunosorbent assay, were evaluated in serum samples from different age groups (114 children, aged from 1 month to 15 years, and 20 adults). The IgG kappa/lambda ratio decreased in the first 6 months and subsequently increased slowly during childhood towards the adult value of 2.0. The IgM kappa/lambda ratio increased at a greater rate than IgG kappa/lambda ratio in the first years of life and thereafter rose slightly throughout childhood to reach an adult value of 1.7. A decreasing IgA kappa/lambda ratio was found from 1 month of age onwards to an adult value of 1.1. The pattern of total kappa/lambda ratio was similar to the IgG kappa/lambda ratio with an adult value of 2.0.

Two families were investigated in which the mothers had selective IgA deficiency and circulating class-specific anti-IgA antibodies. Both gave birth to two children who were found to be IgA deficient. Three of these children developed anti-IgA antibodies before puberty. In vitro immunoglobulin production studies performed in the children of both families revealed an IgA B cell defect combined with IgA-specific excessive T suppressor function in all four. The mechanisms by which transplacental passage of maternal anti-IgA antibodies could have interfered with the developing IgA system in the offspring are discussed.