THE USE OF SPENT RENAL DIALYSIS MEMBRANES FOR THE ISOLATION OF LARGE NUMBERS OF HUMAN NEUTROPHILS FOR BIOCHEMICAL-STUDIES - APPLICATION TO PURIFICATION OF THE MYELOID IGA RECEPTOR (FC-ALPHA-R)

Human neutrophils (PMN) can be eluted from spent Cuprophan renal dialysis membranes in large numbers (10(9)-10(10) per dialyser cartridge) and in relatively high purity by washing the membranes with 0.35 M NaCl. This offers the possibility of isolating relatively large amounts (10(-4)-10(-3) g) of minor PMN proteins such as those expressed on the celt surface. Here the technique is applied to the purification of the neutrophil IgA receptor (Fc-alpha-R). Affinity chromatography on IgA-Sepharose of NP-40 extracts of I-125-labelled PMN isolated from fresh venous blood routinely gave a receptor preparation showing one diffuse band. M(r) 50-70 kDa, upon analysis by SDS-PAGE and autoradiography. When the same method was used with larger numbers of unlabelled PMN from fresh venous blood or renal dialysis membranes a preparation was obtained which gave multiple bands upon analysis by SDS-PAGE silver stained gels due to contamination of the receptor with cytoplasmic proteins which bound non-specifically to the IgA-Sepharose. Most of these contaminants could be removed by chromatography of the IgA-Sepharose eluates on wheat germ agglutinin-Sepharose.