Effect of RNA on the immunological response of rats, induced by Salmonella typhimurium

Rats treated with RNA from normal rat spleen were challenged 5 days later with Salmonella typhimurium. The primary response was delayed and antibody titers significantly lower than controls were observed. Forty eight hours after the secondary challenge the antibody titers were also lower; this difference disappeared five days later. This study confirms the immunological depression produced by RNA. Moreover, it is demonstrated that the RNA action is transitory and that the recovery of secondary response occurs seven days after the second challenge. This action is probably explained at macrophage level.