Enhancement of stromal cell‐derived factor‐1α‐induced chemotaxis for CD4/8 double‐positive thymocytes by fibronectin and laminin in mice

Publisher Website
Google Scholar
Abstract
Summary: Stromal cell‐derived factor‐1α (SDF‐1α) is a chemokine abundantly expressed in the thymus. However, a potential role of SDF‐1α in the thymus has been under consideration, since no appreciable difference was detected in the migratory responsiveness to the SDF‐1α between cortical and medullary thymocytes. In the present study, we examined the effects of extracellular matrix (ECM) on the responsiveness of murine thymocytes to several chemokines including SDF‐1α. In the absence of ECM, chemotactic activity of SDF‐1α for cortical (CD4/8 double‐positive) thymocytes was almost same as that for medullary (CD4 or CD8 single‐positive) thymocytes. In contrast, the chemotactic activity of SDF‐1α for cortical thymocytes was considerably (more than 10‐fold) enhanced by laminin or fibronectin as compared with that for medullary thymocytes. Chemotactic activities of macrophage‐derived chemokine and macrophage inflammatory protein‐3β for both cortical and medullary thymocytes were only slightly enhanced by fibronectin or laminin. Thus, fibronectin and laminin appear to enhance the chemotactic activity of SDF‐1α for cortical thymocytes selectively. Addition of a monoclonal antibody against CD29 showed no inhibitory effect on the enhanced chemotactic activity of SDF‐1α, suggesting that the other unknown receptor(s) is involved in this enhancement. Our present data demonstrate that SDF‐1α in the presence of fibronectin or laminin is involved in the distribution of developing thymocytes.