Proliferative response to the skin-sensitizing contact agent dinitrofluorobenzene in lymph nodes in mice.

Abstract

AbstractWhen dinitrofluorobenzene (DNFB) is applied to the skin in mice, it induces a state of delayed hypersensitivity. During the three days following the application of this contact agent, lymphoblasts accumulate in the diffuse cortex of the lymph node draining the area of sensitization. This accumulation of blast cells – referred to as a blastogenic response – appears to be part of the induction phase of delayed hypersensitivity.This is an investigation into the origin of the cells of the blastogenic response. There is evidence from other studies that lymphocytes immigrate to the lymph nodes draining a site of sensitization. This paper provides complementary evidence that cellular proliferation in the diffuse cortex of the sensitized lymph node is another source for the accumulation of blast cells. This proliferation has been studied by counting mitotic figures, and by autoradiography after giving 3H‐thymidine in order to determine the number of blast cells undergoing DNA synthesis and the duration of the various phases of the cellular reproductive cycle.The results show a high degree of correlation between mitotic figures and blast cells in the diffuse cortex of the sensitized lymph nodes, consistent with a population of dividing blast cells. Approximately 80 percent of the blast cells were in the DNA‐synthetic phase of the reproductive cycle at the peak of the blastogenic response, and the cells were dividing with approximately an eight hour generation time.These results can be interpreted to indicate that the cells of the blastogenic response, although accumulating initially by immigration to the draining lymph node, become a homogeneous, nondifferentiating population of blast cells, all proliferating at near maximal rate to provide the great numbers of blast cells seen three days after application of the sensitizing agent.