Granuloma Induction and Stimulation of the Immune Response in Mice with Trehalose -6,6′-Dimycolate

Abstract

It has recently become evident that a chemically defined glycolipid derived from tubercle bacilli, trehalose-6,6′-dimycolate (cord factor) is able to induce a typical granulomatous response in the lungs of mice after an intravenous injection of as little as 1–5 μg. The cellular composition of the tubercles induced by cord factor is indistinguishable from the caused by living BCG. In both cases the granulomas are composed of epitheloid cells, macrophages and lymphocytes. The effect of cord factor seems to be specific, since neither different wax D preparations nor phosphatidyl inositomannosides from mycobacteria were able to induce comparable granuloma formation. Cord factor injected in the foot pad of mice induced histological changes similar to those following injections of living BCG bacilli. Both materials induced in the draining lymph nodes the formation of granulomas, marked hyperplasia of the lymphoid tissue in the paracortical zone and accumulations of macrophages. In some cases the macrophages were very numerous and replaced part of the lymphoid tissue, especially at the periphery of the nodes. Such an accumulation of macrophages was also evident in the draining lymph nodes after injection of emulsion, wax D and Freund’s adjuvant, but after emulsion and wax D the macrophages were much less prominent.