Fibronectin receptor subunit (alpha 5, alpha 4 and beta 1) mRNA and cell surface expression in human peripheral blood B lymphocytes.

Members of the beta 1 family of heterodimeric adhesion molecules, e.g., the fibronectin receptors alpha 5 beta 1 and alpha 4 beta 1, mediate the binding of leukocytes to extracellular matrix proteins and may also support cell-cell interactions important for homing and localization of leukocytes at sites of immune and inflammatory reactions. In the present investigation, we have examined human peripheral blood B lymphocytes for mRNA and cell surface expression of fibronectin receptor subunits. B cells (CD 19-positive cells) expressed alpha 4 and beta 1, but not alpha 5, on their surface as determined by double immunofluorescence staining. Highly purified B cells, sorted on the basis of lymphocyte light scatter characteristics and the presence of surface IgM, expressed alpha 4, beta 1 and alpha 5 mRNAs. Expression of integrins, such as alpha 4 beta 1, on B lymphocytes may be important for cell-cell interactions that occur during immune responses.