ALTERED IMMUNOGLOBULIN CONCENTRATIONS AND LIGHT-CHAIN RATIOS IN JUVENILE-ONSET MIXED CONNECTIVE-TISSUE DISEASE

Immunological disturbances may result in altered immunoglobulin concen trations and kappa/lambda light chain (kappa/lambda) ratios. We measur ed the kappa/lambda ratios of total serum immunoglobulins and of polyc lonal IgG, A, and M separately as well as concentrations of these immu noglobulins in fourteen patients with juvenile onset mixed connective tissue disease. When comparing the patient group with a reference grou p the mean serum IgG and IgA concentrations were respectively 2.98 G/L (p=0.0012) and 0.79 G/L (p=0.0114) higher in the group of patients wi th juvenile onset mixed connective tissue disease, The mean IgM concen tration was 0.39 G/L (p=0.0002) lower. The mean kappa/lambda ratios of total serum immunoglobulins, serum IgG, and serum IgA were respective ly 0.20 (p=0.0226), 0.28 (p=0.0016) and 0.10 (p=0.0732), higher in the group of patients with mixed connective tissue disease as compared wi th the reference group. Mean serum IgM kappa/lambda ratio, however, wa s 0.21 (p=0.0046) lower. The alterations of the serum immunoglobulin c oncentrations and of the kappa/lambda ratios reflect immunological dis turbances in patients with juvenile onset mixed connective tissue dise ase. The increased concentration of serum IgG and raised IgG kappa/lam bda ratio and decreased concentration of serum IgM with decreased IgM kappa/lambda, ratio indicate that the synthesis of kappa-bearing immun oglobulins mainly is affected.