Function of dendritic cells and changes in T cell proliferation in antigen-induced nonresponsiveness

The ability of dendritic cells (DC) to acquire and present antigen to T cells during antigen-induced nonresponsiveness (AINR) in contact sensitivity was examined by studying cells from lymph nodes draining the sites of antigen challenge. Mice were pretreated on the right flank with either vehicle (AOO), oxazolone (Ox), or fluorescein isothiocyanate (FITC) and challenged 5, 10, or 20 days later with FITC on the left flank. At 5, 10, and 20 days, compared with animals pretreated with vehicle and challenged with FITC, those pretreated and challenged with FITC showed reduced acquisition of antigen by DC and the DC showed a reduced ability to stimulate naive T cells in vitro. Proliferation of T cells immediately on isolation (reflecting in vivo activity) was also reduced. When the time between pretreatment and challenge was extended to 40 days, the proliferative responses and antigen acquisition returned to normal. Animals sensitized with Ox and challenged with FITC showed nonspecific inhibition of T cell proliferation at 5 days only and not at later times and antigen levels on the DC from these animals were normal. The results show that low T cell proliferation during specific AINR in contact sensitivity may be a consequence of reduced acquisition and presentation of antigen by DC.