The relationship between L-chain synthesis and gamma-globulin production.

The simultaneous administration of labeled human gammaG globulin and L-chains to subjects has allowed examination of the metabolic relationship between a component part and the whole immunoglobulin molecule. Studies were carried out in a series of control subjects and in a group of patients where substandard production of gamma-globulin was anticipated, i.e., patients with the nephrotic syndrome on chronic Imuran therapy and patients with uremia. Full expression of the plasma decay curve was obtained for both substances, that for L-chain requiring only 4-5 days except in uremic subjects and that for gamma-globulin requiring up to 30-40 days. Urinary excretion of inorganic iodide was also quantitated for 20-30 days. Equilibrium of the extravascular, vascular, and urinary radioactivity from the labeled gammaG globulin was usually not seen during this time interval suggesting more than one site of catabolism of the protein. Excess L-chain poduction was about 45% of the total L-chain production and probably in no instance could account for the low gamma-globulin production seen in certain patients with renal disease.