Antigen Presenting Properties of a Myeloid Dendritic-Like Cell in Murine Spleen

This paper distinguishes a rare subset of myeloid dendritic-like cells found in mouse spleen from conventional (c) dendritic cells (DC) in terms of phenotype, function and gene expression. These cells are tentatively named “L-DC” since they resemble dendritic-like cells produced in longterm cultures of spleen. L-DC can be distinguished on the basis of their unique phenotype as CD11b(hi)CD11c(lo)MHCII(-)CD43(+)Ly6C(-)Ly6G(-)Siglec-F(-) cells. They demonstrate similar ability as cDC to uptake and retain complex antigens like mannan via mannose receptors, but much lower ability to endocytose and retain soluble antigen. While L-DC differ from cDC by their inability to activate CD4(+) T cells, they are capable of antigen cross-presentation for activation of CD8(+) T cells, although less effectively so than the cDC subsets. In terms of gene expression, CD8(-) cDC and CD8(+) cDC are quite distinct from L-DC. CD8(+) cDC are distinguishable from the other two subsets by expression of CD24a, Clec9a, Xcr1 and Tlr11, while CD8(-) cDC are distinguished by expression of Ccnd1 and H-2Eb2. L-DC are distinct from the two cDC subsets through upregulated expression of Clec4a3, Emr4, Itgam, Csf1r and CD300ld. The L-DC gene profile is quite distinct from that of cDC, confirming a myeloid cell type with distinct antigen presenting properties.