Fig. 4. FHOS is abundantly expressed in splenic littoral cells. (a) FHOS expression in primary hematopoietic cells. RT-PCR of total RNA was performed using internal FHOS-specific primers (Materials and Methods) and demonstrates the ubiquitous expression of FHOS RNA in distinct primary hematopoietic cells (B cells, T cells, monocytes, dendritic cells, FDCs) and certain cell lines (HeLa, JY). Negative control, murine 3T3 cells. (b) FHOS expression in spleen. Normal frozen human spleen was sectioned and analyzed by in situ hybridization. The antisense panel demonstrates high expression of FHOS mRNA in splenic littoral cells, whereas no signal can be detected in the sense panel (control).