Cellular Reaction in the Footpad and Draining Lymph Nodes of Mice Induced by Mycobacterial Fractions and BCG Bacilli

Abstract

Ten micrograms of trehalose-6, 6′-dimycolate (cord factor), injected into the footpad of mice, induced histological changes similar to those following injection of living BCG bacilli. Both materials induced in the draining lymph nodes the formation of granulomas composed of epitheloid cells, macrophages, and small numbers of lymphocytes. Apart from the granulomatous inflammatory process, marked hyperplasia of the lymphoid tissue in the paracortical zone of the nodes and accumulations of macrophages were evident. In some cases, the macrophages were very numerous and replaced part of the lymphoid tissue. Compared to cord factor, wax D showed weak granulomagenic activity. Only slight and transient inflammation was found in the footpads as well as transient slight lymphoid hyperplasia. Wax D also induced small accumulations of macrophages. Complete Freund's adjuvant induced, under the same experimental conditions, large accumulations of macrophages in the draining lymphnode and lymphoid hyperplasia in the paracortical zone. No cellular reaction was seen in the liver, spleen, and lungs after injection of cord factor and BCG into the footpads of the animals. The results and implications are discussed.

Comparable studies of immunostimulating activitiesin vitroamongMycobacterium bovisbacillus Calmette-Guérin (BCG) substrains

“…Mycolic acid linked to trehalose was named ‘cord factor’ due to the cord‐forming characteristics of the bacilli (Ryll et al , 2001). In the host–parasite relationship, TDM has immunostimulatory (adjuvant) (Bekierkunst et al , 1971), granulomagenic (Bekierkunst, 1968), antitumor (Azuma & Seya, 2001) and nonspecific infection prevention activities (Yarkoni & Bekierkunst, 1976) via cytokine‐signaling processes. The synergistic effect of IFN‐γ on the production of NO and cytokines was observed when the endothelial and monocytic/macrophage cell lines were stimulated with TDM‐coated beads or plates (Figs 4 and 8).…”

Granulomatous Hypersensitivity to Trehalose-6,6′-Dimycolate (Cord Factor) in Mice Infected with BCG

“…Both cord factor and living BCG cells induced formation of granulomas, marked hyperplasia of the lymphoid tissue in the paracortical zone, and accumulations of macrophages in the draining lymph nodes. Because no cellular reaction was evident in organs such as liver, spleen, and lungs, it was possible to show that the increased antibody response to an unrelated antigen, which was observed in such animals, is of a local character, dependent on the abovementioned cellular reaction (2)(3)(4). Recently, it became evident that cord factor suppresses the development of urethane-induced tumors in the lungs of mice to an extent similar to that induced by living BCG cells, inhibition apparently due to the granulomatous reaction caused locally in the lungs by cord factor (5).…”

Stimulation of lymphocyte proliferation by killed mycobacteria and other bacterial species

“…In preliminary experiments carried out to see whether mycobacterial cells affect murine thymocytes in the same way as spleen cells, it was found that no stimulation of thymocytes could be achieved. However, from observations in this laboratory and in others, it has been known that there is an increase in T cells, not only in draining lymph nodes of experimental animals but also in humans after administration of BCG (4,12). It has been assumed, in view of the above results obtained in vivo, that mycobacteria can affect thymocytes not directly but indirectly through the intermediary of spleen cells.…”

“…The adjuvant and antitumor activity of living BCG, killed BCG, cord factor (trehalose-6,6'dimycolate), and other mycobacterial fractions is apparently connected with the inflammatory chronic granulomatous reaction of the host that develops at the site of lodgement ofthese agents. This may take place in the skin (6), lymph nodes (4,7,12,13), lungs, or peritoneal cavity (5,16). However, to achieve stimulation of the immune response against unrelated antigens, among them weak tumor-specific antigens, the latter have to be at the same site, where large numbers of macrophages and lymphocytes are attracted and acted upon by the BCG cells (6).…”