Cryofiltration in the treatment of cryoglobulinemia and HLA antibody-incompatible transplantation.

Cryofiltration is a technique in which plasma is separated from blood and chilled, leading to the formation of "cryogel", a composite of heparin, fibronectin, fibrinogen, immunoglobulins, and other proteins. This is retained by further filtration and plasma is returned to the patient. There may be a role for cryofiltration in the treatment of cryoglobulinemia or where the application of other forms of plasmapheresis or immunoadsorption is limited. Five patients received six courses of cryofiltration. Two patients had cryoglobulinemia and three were treated before HLA antibody-incompatible renal transplantation. The treatment was associated with few adverse effects, and it was possible to treat up to 120 mL/kg plasma per session. There was a good clinical response in four patients. One patient was switched back to double filtration plasmapheresis (DFPP) because cryofiltration seemed to remove HLA antibodies less effectively, but the other two transplants have excellent function. In the cryoglobulinemia patients there was excellent clearance of cryoglobulins during each treatment (mean decrease of 78.2 (SD 14.1)% per treatment). Compared with DFPP, fewer immunoglobulins were removed and the mean percentage reductions in immunoglobulin G per treatment were 36.0 (4.0)% for cryoglobulinemia and 59.2 (2.5)% for DFPP (P < 0.01), with respective mean plasma volumes of 64.2 (10.3) and 71.1 (6.8) mL/kg treated. Cryofiltration offers a treatment choice in patients with cryoglobulinemia and in those who may not be able to tolerate high-volume DFPP. The technique used in the patients described here was less effective than DFPP; however, use of an alternative fractionator and treatment of higher plasma volumes may enhance the efficiency of cryofiltration.