Cell preparation in immune response by immune ribonucleic acid. II. Independence of T lymphocytes in immune response against T-independent antigens.

The immune response of congenitally athymic (nude) mice induced by immune ribonucleic acid (iRNA) to lipopolysaccharides of Escherichia coli 0-55 (LPS) was studied. The thymus-independent nature of the immune response of mice to LPS was confirmed and nude mice responded to LPS in a manner similar to normal mice. An iRNA preparation extracted from the spleen of nude mice immunized with LPS could induce the proliferation of rosette-forming cells (RFC) in nude mice. iRNA preparations were insensitive to treatment with deoxyribonuclease and pronase, but were inactivated by ribonuclease treatment. The active fraction of the iRNA preparation had sedimentation values in a sucrose density gradient between 7 and 16 S and comprised only a small fraction of the total RNA present in the spleen cells, thereby indicating that the active moiety was one or more species of RNA. The anamnestic response was induced by treatment with iRNA made from the spleen of nude mice immunized with LPS. An increase in the number of rosette-forming cells (RFC), plaque forming cells (PFC) and formation of humoral antibody to LPS was seen after injection with a small amount of LPS 4 weeks after iRNA treatment.