Expression of Vascular Cell Adhesion Molecule-1 by Follicular Dendritic Cells

Follicular dendritic cells are the major supporting cell of the germinal center microenvironment. The major function of follicular dendritic cells is to present antigen to B cells in secondary lymphoid tissuey. Through cell-cell interactions, FDCs are hypothesized to be central to the regulation of normal B cell growth and differentiation. The major receptor-ligand pair which mediates B cell-FDC adhesion is the βl integrin VLA-4, present on B cells and VCAM-I expressed on FDCs. Follicular nun-Hodgkin's lymphomas similarly employ this mechanism to bind to neoplastic germinal centers. The VCAM-I molecule can exist as a 6 or 7 immunoglobulin domain form. The major form of VCAM-I on activated endothelium is the 7 domain form. In this report we have determined by polymerase chain reaction of purified FDCs that they express predominantly mRNA for 7 domain VCAM-I. It is likely that the two forms of VCAM-I are associated with distinct functions, therefore the expression of 7 domain VCAM-I may be important in norm...