Transplantation, 2000, Vol.69(4), pp.588-597
BACKGROUND.: Cyclosporine A (CsA) and tacrolimus prevent proliferation but not transendothelial migration of alloreactive lymphocytes into donor organs. As a result, serious adverse effects, such as nephrotoxicity and neurotoxicity, have been observed under CsA/tacrolimus therapy. The incorporation of new drugs with infiltration blocking properties might enhance the efficacy of the current immunosuppressive protocol, allowing lower CsA/tacrolimus dosage. Because Ca plays a critical role in cell-cell interaction, the Ca-channel blocker verapamil might be a good cany.didate for supporting CsA/tacrolimus-based therap METHODS.: A T-cell endothelial cell coculture model or immobilized immunoglobulin G globulin chimeras were employed to investigate how S- and R- verapamil interfere with the lymphocytic infiltration process. The expression and arrangement of membranous adhesion receptors and cytoskeletal F-actin filaments were analyzed by fluorometric method in the presence of. verapamil. RESULTS.: Both verapamil enantiomers strongly inhibited lymphocyte infiltration. CD4 and CD8 T-cells were influenced to a similar extent with regard to horizontal locomotion (CD4=CD8), but to a different extent with regard to adhesion and penetration (CD4 〉 CD8). Moreover, penetration was blocked to a higher extent than was adhesion. ID50-values were 31 μM (CD4-adhesion) and 11 μM (CD4-penetration). Verapamil reduced P-selectin expression on endothelial cells and effectively down-regulated binding of T-cells to immobilized P-selectin immunoglobulin G globulins (ID50=4.4 μM; CD4). A verapamil-induced reduction of intracellular F-actin in T-lymphocytes was proven to be mainly responsible for diminished cell locomotion. CONCLUSIONS.: The prevention of CD4 T-cell penetration by verapamil might argue for its use as an adjunct to CsA/tacrolimus-based immunosuppressive therapy.
Immunosuppression ; Endothelium ; Lymphocytes T ; Immunosuppressive Agents ; Cell Motility ; Verapamil ; Calcium Channel Blockers ; Experimental ; Function ; Immunology ; Calcium Channel Blockers ; Cell Motility ; Immunology ; Verapamil;
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