FOLLICULAR DENDRITIC CELLS SPECIFICALLY EXPRESS THE LONG CR2 CD21 ISOFORM/

This paper describes an antibody (mAb 7D6) that specifically recognize s human follicular dendritic cells (FDCs). By expression cloning, a cD NA clone encoding for the long human CR2/CD21 isoform (CD21L) that con tains an additional exon (10a) was isolated. We demonstrated that FDCs selectively express CD21L, while B cells selectively express the shor t CR2/CD21 lacking exon 10a (CD21S). By screening mouse Ltk(-) cells t ransfected with the CD21L cDNA, we further showed that the other two a nti-human FDC mAbs DRC-1 and KiM4 also recognize CD21L. Thus, CD21L re presents the first characterized human FDC-specific molecule, which ma y confer unique functions of FDCs in germinal center development.