Objectives To clarify the mechanism of leukocytapheresis (LCAP) in patients with rheumatoid arthritis (RA).
Methods Protein profiles of blood samples from 2 patients with RA obtained via LCAP column inlet and outlet lines were analyzed by two-dimensional fluorescence difference gel electrophoresis and mass spectrometry. Then, the lactoferrin (LTF) levels of peripheral and circulating blood samples from 7 patients obtained via the LCAP column blood circuit were determined by enzyme-linked immune sorbent assay. Peripheral blood samples from 14 patients with RA were exposed to unwoven polyester fiber filter (filter) and LTF level was determined. In addition, morphological change of neutrophils after exposure to filter was examined by optical microscopy, electronic microscopy and LTF immunostaining.
Results LTF levels were increased both in the samples from the LCAP column outlet and in peripheral blood at the end of LCAP treatment. Furthermore, peripheral blood samples exposed to filter revealed a decreased number of neutrophils and increased level of LTF. Morphological analysis of the exposed neutrophils showed vacuolization of the cytoplasm and degranulation of LTF positive granules. These data suggested that LTF stored in the granules of neutrophils was released from the neutrophils caught in the LCAP column.
Conclusions Because LTF has been reported to have multiple anti-inflammatory properties, increased levels of LTF may contribute to the clinical effect of LCAP in patients with RA.
Disclosure of Interest None declared