Functional deficiencies of spleen dendritic cells in autoimmune MRL/lpr mice

We investigated functional aspects of splenic dendritic cells (DC) obtained from MRL/MpJ-lpr/lpr (MRL/l) mice, and their normal counterparts, MRL/MpJ-+/+ (MRL/+) mice. In vitro antigen-presenting activity of DC obtained from MRL/l mice was impaired compared with that of DC from MRL/+ mice. Another major functional aspect of DC, i.e., stimulator cell activity in the allogeneic mixed lymphocyte reaction (MLR), was also found to be impaired in MRL/l mice. MRL/l mice and MRL/+ mice were also examined for co-operation between macrophages (M luminal diameter) and DC. We found peritoneal resident M luminal diameter obtained not only from MRL/+ mice but also from MRL/l mice released a soluble factor which enhanced the activity of DC from the respective mice. Furthermore, DC from both MRL/l and MRL/+ mice responded to the culture supernatant of a mouse macrophage hybridoma clone, S44, which releases a factor that enhances the antigen-presenting activity of DC, and their activity as stimulator cells in the allogeneic MLR was enhanced. However, the degree of enhancement was less in MRL/l mice than in MRL/+ mice.