NEW MONOCLONAL-ANTIBODIES DIRECTED AGAINST MOUSE FOLLICULAR DENDRITICCELLS

The follicular dendritic cells (FDC) in B-lymphoid follicles are uniqu e reticular cells that retain immune complexes on their surfaces. We d eveloped new monoclonal antibodies (MAb), SKY01, 28, 41, and 49, again st mouse FDC without useful cell markers. Immunohistochemical study of spleen and lymph node tissues from Balb/c, C3H, and C57BL/6 mice reve aled that SKY01 and 49 were highly specific for FDC, whereas SKY28 and 41 reacted with other stromal components as well as FDC. On immunoele ctron microscopy (IEM), reaction products for all MAb were localized o n the surfaces of FDC. In ontogenetic study of Balb/c spleen, FDC prec ursors were not immunodetected with any of the MAb at 1 week after bir th. The FDC that first appeared as immune complex-retaining cells at 2 weeks were a subpopulation of SKY01(-), 49(-), 28(+), and 41(+) retic ular cells. At 3 weeks, FDC were positive for all MAb, like adult sple en. These results indicate that our MAb recognize differentiation anti gens of FDC. Comparative immunohistochemical studies of spleen from at hymic nude and severe combined immunodeficiency mice suggested that B- cells may be required for the differentiation of FDC. Consequently, th ese MAb are considered useful tools for research on FDC.