Studies of a biochemical lesion in experimental tuberculosis in mice. IX. Response of respiratory enzymes in immune mouse liver to cord factor and tuberculin PPD

Proliferative responses of central and peripheral rat lymphocytes elicited by cord factor (trehalose 6,6'-dimycolate)

Cord factor--a mixture of 6,6'-diesters of alpha, alpha-D-trehalose with natural mycolic acids--which is purified from mycobacteria and other microorganisms, is known to have adjuvant activity as well as to enhance nonspecific resistance to infections and tumor development. In this work, trehalose 6,6'-dimycolate (TDM) was found to induce proliferative responses in rat thymus and lymph node cells. With the thymus cells, TDM responses were greater after removal of the adherent cell subpopulation. Consistent with this observation was the finding that addition of phagocytic cells purified from peritoneal or lymph node cell suspensions to nonadherent thymocytes abrogated the response of thymocytes to TDM. With the lymph node cells, the presence or removal of adherent cells had no major consequence on the TDM-induced proliferative response, since similar increases in deoxyribonucleic acid synthesis were observed with unfractionated and nonadherent cells. The difference between the sensitivities of thymus cells and lymph node cells to regulation by adherent cells indicated the existence of more than one type of TDM responder cell in rats. TDM also displayed marked stimulatory activity on thymus and lymph node cells from germ-free rats, ruling out the possibility that TDM might have triggered a specific, secondary, in vitro immune response. Expansion of a selected cell population(s) triggered by TDM may be involved in the manifestation of adjuvant activity and possibly other immunological properties of cord factor.

Effect of anti-cord factor antibody on experimental tuberculosis in mice

Either active immunization with trehalose-6, 6'-dimycolate (cord factor)-methylated bovine serum albumin complex or passive transfer of rabbit anti-cord factor serum induced in mice an enhanced resistance against infection with virulent human Mycobacterium tuberculosis. This suggests that the anti-cord factor antibody exerts an infection-protecting effect by neutralizing the toxic action of cord factor during the course of living virulent infection with tubercle bacilli. The protective effect of active immunization with cord factor-methylated bovine serum albumin complex and of anti-cord factor serum was found to be specific for the tuberculous infection among a number of experimental infections in mice with a variety of cytopathogenic microorganisms tested.

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.