Differential expression of pathogen-recognition molecules between dendritic cell subsets revealed by plasma membrane proteomic analysis.

Dendritic cells (DC) are comprised of several subsets with distinct functions, differing in their capacity to respond to pathogen products. To gain novel insights into their pathogen specificity, we compared the protein composition of the plasma membrane of CD8+ and CD8- DC, directly isolated from mouse spleens. Differences in protein expression were determined using semi-quantitative high-resolution mass spectrometry of label-free plasma membrane-enriched fractions. Our comparative proteomic analysis detected over 1500 proteins, revealing broad differences in expression of pathogen receptors, adhesion molecules and T-cell regulatory molecules. Many of these findings were validated using flow cytometry and Western Blot analysis of integral and luminal surface-associated membrane proteins. This analysis provides major advantages over genomic approaches as it directly measures protein expression at a particular location. Our study highlights the diversity of surface protein expression amongst components of the DC network.