The mouse immune response to the double stranded polyribonucleotide complex poly(G) . poly(C).

Ten inbred strains of mice were immunized with the double stranded polyribonucleotide complex polyguanylic . polycytidylic acid [poly(G) . poly(C)]. While some immunogenic properties of this duplex were comparable to those of other nucleic acids antigens, differences were also noted. High (SJL/J, BALB/c), low (DBA/2, AKR) and intermediate responders were observed; these differences were not abolished by adsorption of the duplex to MBSA. This pattern of immune response is distinct both from that observed with two other synthetic polyribonucleotide double helices [poly(A) . poly(U) and poly(I) . poly(C)] and with single stranded DNA. The anti-poly(G) . poly(C) activity was localized in the 7S region, whether the sera came from high or low responders, from mice immunized with or without a carrier, after one or several injections. In contrast with anti-poly(A) . poly(U) sera which do not react with poly(G) . poly(C), anti-poly(G) . poly(C) exhibited poly(A) . poly(U) binding activity; no clear relationship between the two activities, however, could be demonstrated. Thus a series of immunological properties differentiates poly(G) . poly(C) not only from the natural polydeoxyribonucleotide single stranded DNA, but also, and more unexpectedly, from two other double stranded polyribonucleotide complexes. These observations suggest that the mechanism controlling the antibody response to poly(G) . poly(C) differs from that regulating poly(A) . poly(U) and/or poly(I) . poly(C), and are to be connected with the fact that the anti-poly(G) . poly(C) antibodies occurring in the sera of patients with systemic lupus erythematosus did not correlate with the antibody activities directed toward the other duplexes.