Granulocytes and monocytes apheresis induces upregulation of TGFβ1 in patients with active ulcerative colitis: A possible involvement of soluble HLA-I.

Granulocyte and monocyte apheresis has been used in different immune-mediated disorders, mainly inflammatory bowel diseases. The removal of activated leukocytes and several additional immunomodulatory mechanisms have been so far suggested to explain the anti-inflammatory effects of the treatment. Recent data indicate that, during centrifugation based apheresis, sHLA-I adsorbed to plastic circuits is able to induce TGFβ1 production in activated leukocytes. On these bases, the present study was aimed at analyzing if this model could be applied to a noncentrifugation based apheresis, such as granulocyte and monocyte apheresis. Ten patients with ulcerative colitis were enrolled. Every patient received 5 weekly apheresis treatments. Cellulose acetate beads removed from the column post-GMA were stained by fluorescent anticlass I mAb and examined by fluorescent microscope. Moreover, sFasL plasma concentration, TGFβ1 plasma levels, and the percentage of TGFβ1 positive neutrophils were evaluated before and immediately after each single apheresis. Immunofluorescent images revealed a homogeneous layer of a sHLA-I adsorbed to the surface of the beads recovered following the procedure. sFasL plasma concentration progressively increased both following the procedures and during inter-procedure periods. Consistently, also TGFβ1 plasma levels and the percentage of TGFβ1 positive neutrophils increased during the procedures with a meaningful relationship with sFasL plasma levels. Taken together, these findings suggest that the immunosuppressive effects attributed to granulocyte and monocyte apheresis might depend, at least in part, on the sensitivity of activated leucocytes to the bioactivity of sHLA-I molecules. J. Clin. Apheresis 32:49-55, 2017.