Lymphocyte depletion and immunosuppression with repeated leukapheresis by continuous flow centrifugation

Leukapheresis by continuous flow centrifugation (CFC) was studied in normal volunteers and patients with rheumatoid arthritis to determine whether this procedure, when carried out repeatedly, can cause lympocytopenia and immunosuppression similar to that produced by thoracic duct drainage. The removal of lymphocytes from blood by CFC was maximal in our hands at centrifuge speeds of 900–1300 rpm and could be related directly to blood flow rates. In addition, it was found that the proportional removal of different lymphocyte subpopulations is affected by the position within the plasma-blood cell interface at which lymphocytes are removed during CFC. Repeated leukapheresis, with techniques designed to favor the removal of T lymphocytes, was carried out in 8 patients with rheumatoid arthritis at a rate of 2–3 CFC/wk for periods of 5–7 wk (total CFC were 13–18/patient). Up to 18.6 × 1010 lymphocytes were removed from the patients (mean 13.0 × 1010 lymphocytes) at an average rate of 3.5 × 109 lymphocytes/day, resulting in significant lymphocytopenia in each patient (mean decrease of blood lymphocyte counts, 72%). As has been observed with thoracic duct drainage, in similar patients, decreases in lymphocyte counts occurred most rapidly during the first 10 days of repeated leukapheresis. Lymphocytopenia reflected predominately a loss of circulating T lymphocytes, and in vitro lymphocyte responses to T-cell mitogens were reduced. Lymphocytopenia (lymphocyte counts