Adhesion of MNC to extracellular matrix proteins following in vitro photochemotherapy

Background Photochemotherapy is a safe and effective treatment for patients with drug- resistant serve GvHD. The technique involves the exposure of MNC to psorale n and UVA light (PUVA). We have investigated the effect of in vitro PUVA on MNC adhesion to extracellular matrix (ECM) proteins. methods MNC were isolated from peripheral blood (PB) and umbilical cord blood (UCB) , and treated with PUVA. After labeling by a chemiluminescent probe, MNC we re plated on ECM proteins (collagen, fibrinogen, vitronectin and laminin) a nd the number of adherent cells was measured. Results Untreated MNC from both PB and UCB showed a similar adhesion to the substra tes. As a consequence of exposure to PUVA, most of PB samples shows signifi cantly enhanced adhesion to the ECM proteins; on the other hand, UCB- recov ered MNC did not significantly modified their adhesion Discussion MNC adhesion to ECM components is mediated by integrins a family of cell me mbrane; the ligand-binding affinity of certain integrins may be modulated b y different stimuli. PUVA treatment of PB-recovered MNC may induce the up-r egulation of the ligand-binding affinity of the integrins involved in the a dhesion to ECM proteins. The finding of unmodified UCB cell adhesion after PUVA, may be related to the functional immaturity of lymphocytes at birth.