CD8+CD62LhiCD25-cells induce skin inflammation in a psoriasis-like disease model and exhibit a Th1 phenotype

Previously we have shown that adoptive transfer of CD4+CD45RBhiCD25- T cells (naïve CD4 cells), into scid/scid mice can induce psoriasis-like disease. The affected mice develop scaly and raised skin plaques and immune features in this model mimic those of human psoriasis. Data from others suggests that skin infiltrating CD8+ T cells contribute to disease exacerbations in human psoriasis. To understand the role of CD8 cells in the mouse model of psoriasis, we adoptively transferred either naïve CD4 T cells, or CD8+ CD62LhiCD25- cells (naïve CD8 T cells) or combined naïve CD4 and CD8 cells into scid/scid mice and monitored disease progression. We found that adoptive transfer of naïve CD8+ T cells alone resulted in slightly less severe skin lesions when compared to either naïve CD4 T cell transfer or combined CD4 and CD8 T cell transfer. We also found that mice receiving CD8+ T cells experienced slightly reduced epidermal hyperplasia and inflammation than mice given other combinations of T cell transfer. Quantitative RT-PCR analysis of the mouse ear RNA and intracellular cytokine staining of the draining lymph node cells from these mice revealed that in comparison to mice given naïve CD4 cells, mice receiving CD8 cells expressed mainly a Th1 cytokine profile. Results here suggest that CD8 cells may also play an important role in perpetuating the development of skin lesions and exhibit mainly a Th1 phenotype.