STIMULATION OF IGA SYNTHESIS IN THE LUNGS BY ORAL IMMUNIZATION - A PROSPECT OF THERAPEUTIC RELEVANCE

Due to its strategic position on mucosal surfaces secretory immunoglob ulin A (sIgA) is one of the first protective factors of the specific i mmune system against invading pathogens. As a factor of acquired immun ity, the synthesis of sIgA can be modulated by various immunization st rategies. Our experiments aimed at the enhancement of the sIgA pool in the lungs by oral immunization, As reported previously, commercially available LW 50020, an immunomodulator consisting of lysates of seven common pneumotropic pathogens, is effective in inducing significant Ig A antibody responses in the lungs following oral immunization [1]. In the present study we developed new strategies to enhance this effect b y encapsulating LW 50020 into microspheres and liposomes. Microspheres and liposomes with entrapped. immunomodulator each enhanced the effec t of soluble LW 50020 by about 45% and 90%, respectively. In addition, microsphere based immunization induced a significantly increased immu noglobulin G (IgG) response in the lungs. In further experiments we de monstrated that a similar effect could be achieved by-administration o f a high molecular weight conjugate of lipopolysaccharide from Klebsie lla pneumoniae (LPS) and lipoteichoic acid from Streptococcus pyogenes (LTA). This conjugate enhanced the synthesis of IgA in the lungs by 4 5% and, furthermore, induced a significantly enhanced IgG response in the lungs, without any obvious toxic or pyrogenic side effects. This n ew conjugate possibly offers an opportunity to replace the complex imm unomodulator LW 50020 by a less complex vaccine.