Lymphocytes treated by extracorporeal photopheresis demonstrate a drop in the Bcl-2/Bax ratio: a possible mechanism involved in extracorporeal-photopheresis-induced apoptosis.
BACKGROUND
Recently, apoptosis has been identified in treated lymphocytes, prior to their re-infusion, when tested ex vivo. Previous work has demonstrated a close association between the genes p53, Bcl-2 and Bax and apoptosis induced by UV irradiation.


OBJECTIVE
We wanted to establish whether the expression of the protein product of these genes was altered in lymphocytes treated with extracorporeal photopheresis (ECP) prior to re-infusion and therefore possibly implicated in the early apoptosis observed.


METHODS
Lymphocytes were isolated immediately before treatment and immediately prior to re-infusion and tested for intracellular levels of p53, Bcl-2 and Bax proteins.


RESULTS
No increase in p53 expression was observed at re-infusion; however, the mean fluorescent intensity ratio of the apoptotic inhibitor protein Bcl-2 to the apoptosis-inducing protein Bax dropped significantly.


CONCLUSIONS
The early apoptosis observed in ECP-treated lymphocytes at re-infusion might be attributed to dysregulation in the expression of the apoptotic genes Bcl-2 and Bax.
Bladon
J
J
Haematology, Rotherham Hospital, Rotherham, UK. john.bladon@rgh-tr.trent.nhs.uk
Taylor
P C
PC
D017209:Apoptosis / Q000502:physiology / Q000528:radiation effects*; D005434:Flow Cytometry; D015870:Gene Expression / Q000528:radiation effects; D019254:Genes, bcl-2 / Q000528:radiation effects*; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism* / Q000528:radiation effects; D016399:Lymphoma, T-Cell / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D017893:Photopheresis; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D051028:bcl-2-Associated X Protein
C494826:BAX protein, human; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein