Effect of ageing of serum on consumption of antibody by beta-1C-globulin determinants; evidence for circulating breakdown products in glomerulonephritis.

Abstract

Changes in antibody consumption by the A and D determinants of β1C-globulin were found to increase as serum aged in vitro. Consumption by the A determinant was 1·6 times and by the D determinant, 2·5–3 times greater in aged serum than in fresh EDTA plasma. The most likely explanation for the increased consumption with ageing is steric changes occurring as the β1C molecule fragments into β1A and α2D, resulting in exposure of additional antibody combining sites. In specimens from patients with hypocomplementemic nephritis, the increase in consumption with ageing was less than in normal subjects. The data add to the evidence presented in earlier studies of the presence in vivo, in certain nephritics, of breakdown products of β1C-globulin. The most abundant breakdown product would be α2D-globulin.