Total lymphoid irradiation retards evolution of articular erosions in collagen induced arthritis

Collagen induced arthritis was elicited in rats and monitored with serial magnification radiographs and serologic studies. Total lymphoid irradiation (TLI), 1050 rad in 3 fractions, was given at 1 of 2 days after primary immunization. Erosive arthritis and periostitis evolved more slowly in rats irradiated on Day 9 compared to nonirradiated control animals; in contrast, rats irradiated on Day 21 showed no significant differences. At Day 114 neither group receiving TLI differed from nonirradiated controls. Additional groups of rats were irradiated at varying times relative to collagen immunization. On Day 18 the mean IgM and IgG anticollagen antibody responses were transiently decreased in animals receiving TLI by Day 9, with no differences by Day 36.