BINDING OF CANDIDA-ALBICANS YEAST-CELLS TO MOUSE POPLITEAL LYMPH-NODETISSUE IS MEDIATED BY MACROPHAGES

We previously reported that Candida albicans yeast cells adhere to the macrophage-rich medullary and subcapsular sinus areas of mouse lymph node tissue. To determine whether the yeast cell-lymph node interactio n is mediated by macrophages, the effect of specific elimination of ma crophages on yeast cell binding was studied, and yeast cell adherence was correlated with the ingestion of India ink by lymph node cells. Ma crophage elimination was done by use of liposome-containing dichlorome thylene diphosphonate (L-Cl2MDP). Mice were injected in the hind footp ads with the L-Cl2MDP preparation, popliteal lymph nodes were removed 5 days later, and yeast cell adherence was determined by an ex vivo bi nding assay. As controls, lymph nodes from mice that received footpad injections of either phosphate-buffered saline (PBS) alone or liposome -containing PBS were used. Use of macrophage- and neutrophil-specific monoclonal antibodies in tissue immunostaining showed that the L-Cl2MD P treatment eliminated macrophages but not neutrophils from the medull ary and subcapsular sinus areas of the popliteal lymph nodes. A striki ng reduction of yeast cell adherence occurred with lymph nodes from L- Cl2MDP-treated mice compared with lymph nodes from control animals. Th e lymph node-yeast cell binding patterns of L-Cl2MDP-treated and contr ol mice were the same regardless of mouse strain, sex, or T-cell compe tency. Results of India ink experiments, in which India ink was inject ed into footpads of mice and was rapidly taken up by popliteal lymph n ode macrophages, showed a strong correlation between yeast adherence a nd India ink staining of cells. In addition, the interaction of yeast cells with lymph node tissue from normal mice was not significantly af fected by the addition of two extracellular matrix proteins, fibronect in and laminin, during the ex vivo adherence assay. These data indicat e that medullary and subcapsular sinus lymph node macrophages express an adhesion system similar to that described for mouse splenic margina l zone macrophages.