A hemoperfusion column selectively adsorbs LAP+ lymphocytes to improve anti-tumor immunity and survival of tumor-bearing rats
A decrease of immune suppressive cells in blood is thought to be one of the means to activate anti-tumor immunity that works as a treatment for cancers. We have developed an adsorbent that selectively adsorbs lymphocytes expressing latency-associated peptide (LAP), which include regulatory T cells (Tregs). The adsorbent, diethylenetriamine-conjugated polysulfone coated on polyethylene terephthalate fibers, was packed in a column for direct hemoperfusion (DHP). The therapeutic efficacy of DHP with the column was examined in rats carrying KDH-V liver cancer cells, in which LAP+ cells were increased in blood. After DHP, LAP+ T cells were decreased in peripheral blood, and a cytotoxic T-lymphocyte response against KDH-V cells was increased in tumor-bearing rats that had been immunized with X ray-irradiated KDH-V cells. Furthermore, the survival time of the rats was longer than that of rats without DHP. Thus, the removal of LAP+ T cells can potentially be applied to the treatment of cancer regardless of the origin since an increase in the number of LAP+ cells has been observed in the peripheral blood of various cancer patients.