Comparison of the mode of immunopotentiating action of BCG and wax D. I. Effect on the immune response to SRBC.

The immunopotentiating action of BCG and wax D was comparatively evaluated as the immune response to sheep red blood cells (SRBC) in mice. The immunopotentiation of BCG varied with the interval between its priming and subsequent antigen injection. BCG increased delayed type hypersensitivity (DTH) at early stage but enhanced antibody formation at later stage. DTH reached its maximum about 5 weeks after BCG inoculation. In contrast, wax D increased antibody formation at early stage but increased DTH at later stage. Freund complete adjuvant (FCA) containing wax D stimulated much antibody formation rather than induction of DTH in mice. Cord factor and even Drakeol 6VR could induce DTH at early stage of prior inoculation.

Hydrosoluble immunostimulants of bacterial and synthetic origins.

The role of whole Mycobacteria, mycobacterial cell walls and waxes D as immunostimulants was well established many years ago. More recently three different research groups have shown that hydrosoluble components from mycobacterial and other bacterial origins were as active as waxes D or cell walls and were free of many side-effects. Studies concerning the relationship between structure and activity were achieved which led to the description of a small biologically active fragment and to a first series of synthetic compounds.

Synergism of immunogenic and adjuvant-active components of mycobacterial wax D in the induction of adjuvant arthritis.

Two derivatives of wax D, one possessing immunogenicity and the other adjuvant activity, were tested for the possible role in the induction of adjuvant arthritis (AA) in rats. The former, a water-soluble arthritogenic and immunogenic component (WAC), in incomplete Freund's adjuvant, was able to induce delayed hypersensitivity (DH) and mild AA, but failed to function as an adjuvant in rats. The latter, an acetylated wax D (AD) and its subfraction, AD6, did exert adjuvant activity, but were free from immunogenicity and arthritogenicity. The addition of AD or AD6 to the WAC in incomplete Freund's adjuvant, when injected into inguinal lymph nodes, resulted in the production of severe AA with high incidence. Other adjuvants such as pertussis vaccine and lipopolysaccharide could not replace AD6; they failed to enhance AA when combined with the WAC. Also, other mycobacterial antigen, PPD, could not replace wax D-derived WAC; it did not induce AA when coupled with AD6, although it did induce DH to PPD.