The nature of murine immune response to nucleic acids

The antibody response of mice to nucleic acids appears to be genetically regulated, and may show varying patterns. SJL/J mice and AKR/Cu mice are high responders to denatured DNA complexed with MBSA and produce 7S as well as 19S antibodies. DBA/2 mice respond with low titers to this immunogen which consists of 19S antibody exclusively. C57BL/6 mice are high responders to denatured DNA, but produce only 19S antibodies. Denatured DNA-MBSA is immunogenic when injected without complete Freund's adjuvant, thereby suggesting that this antigen might be thymus independent. The pattern of immune responses of some strains to the polyribonucleotides poly(I)-poly(C) and poly(A)-poly(U) is opposite to that observed with denatured DNA. Thus, DBA/2 mice are high responders and SJL/J mice are low responders. However, the low responders SJL/J mice produce 7S as well as 19S antibody which suggests that different mechanisms operate for the regulation of immune responses to the two types of nucleic acids. Whereas no antibody is elicited upon immunization with DNA in the absence of a carrier protein, poly(A)-poly(U) and poly(I)-poly(C) are immunogenic when injected without MBSA. Immunization with complexes of the polyribonucleotides and MBSA enhanced the responses to these immunogens; however, the strain differences were not completely abolished. Poly(A)-poly(U) did not enhance the low immune responses of DBA/2 mice to denatured DNA when injected i.v. following immunization with the DNA-MBSA. However, simultaneous immunization of DBA/2 and SJL/J mice with poly(A)-poly(U) and denatured DNA-MBSA resulted in high antibody titers to both immunogens in either mouse strain.