Preliminary studies for the development of a second generation granulocytapheresis (G-CAP) column

The preliminary studies for developing a second generation granulocytapheresis (G-CAP) column were made. In the past, the G-CAP column has been used for the treatment of ulcerative colitis and rheumatoid arthritis. However, recent clinical studies have revealed that the therapeutic effects of the G-CAP column are not significant compared with those of the sham column. These results were considered to be due to insufficient reduction of granulocytes. Thus, development of a better granulocyte removal column was attempted. Realizing that white cells adhered on small-diameter synthetic fibers of 1–2 μm, small diameter cotton fibers were subjected to the studies of their granulocyte-removing capabilities. Three types of cotton, Pakistani, Australian and Egyptian cottons, were evaluated using normal human blood in vitro. Miniature columns were made of each fiber, and CBC and WBC differentiation was compared between pre- and post-filtered blood. The Egyptian cotton removed leukocytes, especially granulocytes, the most efficiently of the three types of cotton. The Egyptian cotton’s granulocyte adhesion properties were not altered after different chemical treatments. A 4-ml column of packaged Egyptian cotton with a density of more than 0.125 g/ml could remove granulocytes effectively up to 80 ml of blood passages. Based upon these studies, second generation G-CAP could be carried out with Egyptian cotton fibers as a scaled-up clinical module.