Neutrophil activation in immunoadsorption.

Immunoadsorption therapy (IAT) is used in the treatment of autoimmune diseases. Although IAT has been reported to modify humoral immunity by inducing chemokines and activating complements, much remains unknown about the biological effects of IAT on cellular components in peripheral blood. To define the influence of IAT on leukocytes, we determined leukocyte L-selectin (CD62L) and Mac-1 (CD11b) as parameters for activation of leukocytes in peripheral blood during IAT. Peripheral leukocyte L-selectin and Mac-1 were determined continuously by flow cytometry in 6 patients with neuroimmunological disorders in whom IAT was conducted using a Plasma Flow OP-05 (Asahi Medical Corp., Tokyo, Japan) as a plasma separator and Immusorba TR-350 (Asahi Medical Corp., Tokyo, Japan) as an adsorption column. Expression of neutrophils (PMN) L-selectin was decreased 30 min after starting IAT, with the decreases particularly marked at the end of IAT, while expression of mononuclear cells (MNC) L-selectin slightly increased during IAT. Expression of PMN Mac-1 was markedly increased at the end of IAT, whereas expression of MNC Mac-1 did not change during IAT. Leukocyte counts decreased 30 min after starting IAT, and then increased to the initial level or higher in parallel with L-selectin downregulation and Mac-1 upregulation on PMN. L-selectin downregulation and Mac-1 upregulation on PMN suggested that activation of PMN associated with changes in peripheral leukocyte counts occurred during IAT and might play some role in modulating the human circulating blood and immune systems.