A thermoconductive and thermoselective leukocyte filter

Previously, it was reported by our group that the superphysiological temperature of over 43 degrees C affected leukocyte properties. It was speculated that heat treatment might alter the immunological properties of leukocytes. In order to take advantages of this phenomenon, attempts were made to develop a thermoconductive and thermoselective leukocyte filter. A stainless steel fiber was selected for the new material of a leukocyte filter due to its good heat conductance, stability during thermal change, and inertness to any chemicals. Preliminary studies were conducted to evaluate the effect of fiber diameter and temperature on the filtration of blood cells. As a result, more than 99% of white blood cells (WBCs) and platelets were removed utilizing a 4 microns diameter fiber filter. The environmental temperatures of the filtration process were varied to 4, 20, 36, and 50 degrees C for 5 min. Almost 95% of WBCs and platelets were removed at 4, 20, and 36 degrees C. However, the reduction of platelets was remarkably suppressed at 50 degrees C (54%). Additionally, the removal of lymphocytes was significantly lower than that of neutrophils at 50 degrees C (69% vs. 83%; p = 0.0002). These data demonstrate that effective heat treatment and removal of leukocytes are possible with an ultrafine stainless steel fiber filter.