Table 1.

Stromal cells in SLO.

Name	Location	Phenotype	Function
Follicular dendritic cell (FDC)	Cortex, B cell primary follicle (LN and spleen)	CD45−CD35+ FDC-M1+	Regulate B cell homeostasis, migration, and survival (Gunn et al., 1998a; Hase et al., 2004; Munoz-Fernandez et al., 2006) Express complement and Fc receptors and are able to trap immune complexes to present B cells (Aguzzi and Krautler, 2010) Activate B cells by presenting exogenous antigen (El Shikh et al., 2010) Express CXCL13, attracting naïve B cells expressing CXCR5 (Aguzzi and Krautler, 2010)
Fibroblastic reticular cell (FRC)	Paracortex, T cell area (LN and spleen)	CD45− gp38(podoplanin)+ CD31− ER-TR7+ VCAM-1high CD44high	Support B cell, T cell, and DC interactions (Katakai et al., 2004a; Bajenoff et al., 2006) Directly induce tolerance of responding naïve CD8 T cells (Lee et al., 2007) Express peripheral tissue antigens (PTAs) Present antigens to stimulate naïve T cells (Fletcher et al., 2010b) Secrete collagen and other extracellular matrix (Fletcher et al., 2010a) Create a conduit system of fine microchannels that conduct small lymph-borne antigens and inflammatory mediators deep into the LN paracortex B cells use the FRC network to reach the follicles Express CCL19, CCL21, and SDF1 (CXCL12; Luther et al., 2000) Express IL-7 which promotes survival of naïve T cells (Link et al., 2007)
Lymphatic endothelial cell (LEC)	LN	CD45− gp38+CD31+ VCAM-1low CD44low	Directly induce tolerance of responding naïve CD8 T cell (Cohen et al., 2010) Regulate T cell entry to and exit from LNs
Blood endothelial cell (BEC)	LN and spleen	CD45−gp38− CD31+ VCAM-1low CD44low	Express PTAs (Cohen et al., 2010; Fletcher et al., 2010b) Regulate T cell entry to and exit from LNs
Double negative (DN)		CD45−gp38−CD31−	Express PTAs (Cohen et al., 2010; Fletcher et al., 2010b)