Follicular dendritic cells (FDCs) are large cells in germinal centers (GCs) of primary and lymphoid tissues. They present non-processed antigen and switch off apoptosis of B cells through a selection process resulting in selection of memory B cells. They express many B cell markers such as CD21 (long isoform), CD23 and CD35.The hybridoma CNA.42 recognizes a unique carbohydrate epitope found on FDCs from a variety of species.It has been shown to be a useful reagent for both flow cytometry and IHC analysis.