DIFFERENCE IN CAPACITY BETWEEN MACROPHAGES AND DENDRITIC CELLS FROM RAT INCISOR PULP TO PROVIDE ACCESSORY SIGNALS TO CONCANAVALIN-A-STIMULATED T-LYMPHOCYTES

The present study compared the ability of dendritic cells and macropha ges derived from the dental pulp to provide accessory signals to Conca navalin A (Con A)-stimulated T-lymphocytes. Pulpal cells from maxillar y and mandibular rat incisors were enzymatically released with collage nase. T-lymphocytes were isolated from rat cervical lymph nodes. In in itial experiments, suspensions of unseparated pulpal cells were found to provide costimulatory help to Con-A-treated T-lymphocytes. The prol iferation rate correlated well with the number of cells in the pulp su spension and followed a time course characteristic of a Con-A-driven p roliferation of T-lymphocytes. Depletion of class II molecule-expressi ng cells from the unpurified suspension of pulpal cells resulted in lo st ability to provide accessory signals to Con-A-stimulated T-lymphocy tes. In contrast, removal of ED2-positive cells, i.e., macrophages, di d not affect the ability of the suspension to give this assistance. Pa rtially purified class II molecule-expressing cells enhanced the proli ferative response, while addition of enriched macrophages did not. It was concluded that cells in the normal dental pulp with the characteri stics of dendritic cells have the capacity to provide help to Con-A-st imulated T-lymphocytes, while cells with the macrophage phenotype lack this ability.