Antibody formation to trehalose-6,6'-dimycolate (cord factor) of Mycobacterium tuberculosis.

A complex of trehalose-6, 6'-dimycolate (cord factor) and methylated bovine serum albumin was prepared, and its effect on the toxicity of cord factor in mice was studied. Either the active immunization with cord factor-methylated bovine serum albumin complex or the passive transfer of sera of rabbits vaccinated with the complex protected mice against the toxic action of cord factor. The antisera of mice and rabbits and gamma globulin fraction of rabbit antiserum demonstrated a precipitin reaction with an aqueous emulsion of cord factor. The reactivity of anticord factor was totally lost by treatment with 2-mercaptoethanol. The antigenic determinant group of cord factor was alpha-d-trehalose. Cord factor-anticord factor complex was devoid of activity to induce in vitro swelling and inhibition of respiratory and phosphorylative activity of mouse liver mitochondria. These results suggest that vaccination with cord factor-methylated bovine serum albumin complex induced the production of antibody to cord factor in mouse and rabbit serum which binds to cord factor and neutralizes its toxic activity either in vivo or in vitro.