[The immunological activity of Neisseria meningitidis lipo-oligosaccharide incorporated into liposomes].

Immune response to lipooligosaccharide (LOS), isolated from group B N. meningitidis cell wall, was studied after its incorporation into liposomes. The adjuvant effect produced by liposomal LOS, more pronounced in comparison with that produced by native LOS, was observed after the injection of the preparation by different routes (intravenous, intraperitoneal and subcutaneous injections), but the highest level of response was achieved after the intravenous and intraperitoneal injections of the preparation. Experiments aimed at the study of the dynamics of plaque-forming cells and the level of antibodies after intraperitoneal immunization of CBA mice with LOS revealed that immune response to liposomal LOS was more intense and prolonged than that to the free antigen. Liposomal LOS induced genetically nonrestricted and T-independent immune response. This fact was confirmed in experiments on mice having different haplotypes, such as CBA (k), C57BL/6 (b), BALB/c (d) and in nude mice with congenital thymic aplasia. In addition, liposomal LOS induced mainly the accumulation of IgM and IgG and did not produce the effect of immunological memory.