Expression of beta-catenins and cadherins by follicular dendritic cells inhuman lymph nodes

In lymph nodes, dendritic cells form a complex meshwork and are linked by i ntercellular junctions. Intercellular junctions contribute to the integrity of lymphatic follicles and can potentially be affected by malignant proces ses in neighbouring B cells. We examined whether transmembrane molecules th at constitute "adherens junctions" are present in follicular dendritic cell s of normal human lymph nodes. We found that follicular dendritic cells but not interdigitating dendritic cells or sinus lining cells expressed cadher in molecules. Follicular dendritic cells also expressed beta -catenin but n ot vinculin. The cadherin molecules, which were identified in situ with the use of a monoclonal pan-cadherin antibody, were not recognized by antibodi es to E-cadherin, N-cadherin or beta -cadherin. Intrafollicularly, cadherin s were clearly colocalized with beta -catenins, in a dot-like fashion. We a lso detected intrafollicular expression of desmogleins and desmosomal plaqu e proteins. These findings indicate the presence of desmosomes within the d endritic meshwork. However, pan-cadherin reactivity was not only colocalize d with desmoglein immunoreactivity that was abundantly present. Immunopreci pitation showed that pan-cadherin reactivity was absent in fractions of des mosomal plaque proteins or pan-desmogleins. We speculate that complexes of cadherins of an unknown subclass and beta -catenins form non-desmosomal int ercellular junctions in the intrafollicular dendritic meshwork.