The role of various chemical fractions of M. tuberculosis and other Mycobacteria in the production of allergic encephalomyelitis

Abstract

A single dose of 1 mg. of wax D fractions of several different strains of human type M. tuberculosis when injected in water-in-oil emulsion together with 16 mg. of homologous brain caused a high percentage of guinea pigs to develop encephalitis. Wax D fractions of several strains of bovine type and one strain of avian type M. tuberculosis and of M. phlei were found ineffective in inducing encephalitis when injected in the same dose and under similar conditions, although M. phlei and delipidated bovine type M. tuberculosis Marmorek bacilli were effective. Cord factor (trehalose dimycolate) and crude wax C fractions from human type M. tuberculosis were ineffective. These results are discussed in relation to the suggestion that the encephalitogenic activity of mycobacteria is due to the presence of a peptide consisting of alanine, glutamic and diaminopimelic acids linked to a glycolipid.

The precise correspondence between the activity of a wide variety of bacillary fractions as encephalitogenic agents in causing an increase in serum antibody to ovalbumin, and in inducing severe corneal reactivity to ovalbumin gives further support to the hypothesis that the encephalitis is the result of an isoimmunization process, in which the mycobacteria increase the immune response to an antigenic constituent of the brain tissue.

Encephalitogenic bacillary fractions produce histological reactions at the injection site and in the draining lymph nodes characterized by the formation of large numbers of epithelioid cells. It is suggested that these cells play an essential rôle in the adjuvant response.