Preparation Of Factor IX-Deficient Human Plasma Using RFF-IX/1 Monoclonal Antibody

A cell line that secretes a monoclonal antibody to factor IX has been produced by fusing spleen cells from a mouse that had been hyper immunised to purified factor IX with mouse myeloma cells (line P3-NSI/I-Ag4-1). Hybrid cells were selected and a monoclonal cell line has been established in culture. This cell line secretes an IgGl(k) antibody (RFF-IX/1) with high affinity for a site related to the coagulant function of factor IX.Monoclonal antibody was partially purified from ascitic fluid from mice implanted with the RFF-IX/1 secreting cells by precipitation at 50% saturation with ammonium sulphate. This fraction has typically 630 NIH units/ml anti IX activity and 13.5 mg/ml protein. It was coupled to cyanogen bromide activated Sepharose 2B in the ratio of 9 mg. protein/1 ml gel. A column containing 10 ml of this gel removed all the assayable factor IX from the first 280 ml of normal ci.trated plasma that was passed over it. After that volume small amounts of factor IX could be detected in the effluent. Subsequently 10-20% of the factor IX activity adsorbed could be recovered by eluting the column with 3 M potassium iodide.Immuno-affinity depleted plasma could be used as substrate in a one-stage factor IX assay under routine laboratory conditions and was undistinguishable for that purpose from severe Christmas disease plasma.

Acquisition of cell surface IgD after in vitro culture of neoplastic B cells from the murine tumor BCL1.

Murine BCL1 tumor cells bear large amounts of surface IgM and trace amounts of surface IgD. In the present studies we have shown that cultivation of these cells, in the absence of lipopolysaccharide, results in the acquisition of IgD by virtually all the cells. These results suggest that BCL1 cells can differentiate in vitro into more mature B cells and offer an attractive model for analyzing the factors controlling appearance of IgD on a monoclonal cell line.