Immune-induced vascular connective tissue alterations in rabbits chronically immunized with bovine serum albumin: biochemical studies on collagen, glycosaminoglycans, RNA, and DNA in normal and injured aorta

Immune-induced dermal connective tissue alterations in rabbits chronically immunized with bovine serum albumin: biochemical studies on collagen, glycosaminoglycans, RNA, and DNA

Rabbits were chronically immunized by repeated intravenous injections of bovine serum albumin and compared to saline injected controls. All sensitized animals developed antibodies to albumin, but in only a few were circulating immune complexes detected. The dermal biosynthesis of dermatan and heparan sulfate in vivo was significantly restrained following immunization due to a reduced cellular synthesis. The collagen type III/I ratio was significantly repressed in the skin of immunized rabbits, in particular in the acid soluble collagen fraction containing newly formed collagen. Further, the hydroxyproline/DNA ratio, expressing the collagen accumulation per cell, was increased, indicating that the secretion of collagen type I was enhanced. These alterations in the formation and accumulation of matrix components were not correlated to the occurrence of circulating immune complexes or the antibody response. Thus, compared to previous investigations on vascular connective tissue, persistent immunostimulation may alter connective tissue metabolism systemically, and it appears that the metabolism of matrix components characteristic of early connective tissue formation and inflammation is particularly susceptible. These observations may be of significance as regards systemic involvement and chronicity in various inflammatory connective tissue diseases.