Treatment of cutaneous T cell lymphoma with extracorporeal photopheresis induces Fas-ligand expression on treated T cells, but does not suppress the expression of co-stimulatory molecules on monocytes.
Following extracorporeal photopheresis (ECP), lymphocytes become apoptotic and upregulate class I MHC antigenic peptides. Conversely, ECP treated monocytes demonstrate activation markers and have an increased avidity for the phagocytosis of apoptotic T cells. Processing of apoptotic T cells by monocytes, following ECP, is thought to induce an immunomodulatory response, which targets untreated, but clonal T cells. Recently we detected apoptotic lymphocytes immediately post ECP. Although enhanced CD95 (Fas) expression has been observed 24 h post ECP, CD95 and Fas-ligand (Fas-L) expression have not been determined at this very early apoptotic stage. Exposure of monocytes to UV has previously suppressed expression of the co-stimulatory molecules required for the presentation of processed antigens to T cells. Our data demonstrate no increase in CD95 or Fas-L expression on T cells tested immediately following ECP. However, the number of T cells expressing Fas-L significantly increased 24 h post ECP (P<0.005). The expression of the co-stimulatory molecules, CD54, CD80 and CD86, remained unaltered on monocytes treated by ECP. Although the mechanism responsible for early induction of lymphocyte apoptosis remains unclear, the later apoptosis involves Fas-L expression. The maintenance of co-stimulatory molecules, on treated monocytes, indicates that they retain the ability to induce an immunomodulatory response.
Bladon
J
J
Department of Haematology, Rotherham General Hospital, Rotherham, South Yorkshire S60 2UD, UK. john.bladon@rothgen.nhs.uk
Taylor
P C
PC
D015703:Antigens, CD / Q000378:metabolism*; D018122:B7-1 Antigen / Q000378:metabolism; D051940:B7-2 Antigen; D002478:Cells, Cultured; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D016410:Lymphoma, T-Cell, Cutaneous / Q000097:blood / Q000378:metabolism* / Q000628:therapy*; D008562:Membrane Glycoproteins / Q000378:metabolism; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D017893:Photopheresis / Q000379:methods*; D012878:Skin Neoplasms / Q000097:blood / Q000378:metabolism / Q000628:therapy; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D014407:Tumor Cells, Cultured; D019014:fas Receptor / Q000378:metabolism
D015703:Antigens, CD; D018122:B7-1 Antigen; D051940:B7-2 Antigen; C497964:CD86 protein, human; D008562:Membrane Glycoproteins; D019014:fas Receptor; D018799:Intercellular Adhesion Molecule-1