H(1)R expression by CD11B(+) cells is not required for susceptibility to experimental allergic encephalomyelitis

The histamine H(1) receptor (Hrh1/H(1)R) was identified as an autoimmune disease gene in experimental allergic encephalomyelitis (EAE), the principal autoimmune model of multiple sclerosis (MS). Previously, we showed that selective re-expression of H(1)R by endothelial cells or T cells in H(1)RKO mice significantly reduced or complemented EAE severity and cytokine responses, respectively. H(1)R regulates innate immune cells, which in turn influences peripheral and central nervous system CD4(+) T cell effector responses. Therefore, we selectively re-expressed H(1)R in CD11b(+) cells of H(1)RKO mice to test the hypothesis that H(1)R signaling in these cells contributes to EAE susceptibility. We demonstrate that transgenic re-expression of H(1)R by H(1)RKO-CD11b(+) cells neither complements EAE susceptibility nor T cell cytokine responses highlighting the cell-specific effects of Hrh1 in the pathogenesis of EAE and MS, and the need for cell-specific targeting in optimizing therapeutic interventions based on such genes.