A method is described for the rapid identification and isolation of cells based on the presence or absence of an ectopically-expressed N-acetyllactosaminide 3-.alpha. Galactosyltransferase (.alpha.GT) enzyme for the production of .alpha.Galactosyl-(1,3)Galactosyl (.alpha.Gal) epitopes on the surface of .alpha.Gal-negative cells. These cells which are genetically modified to express the .alpha.GT enzyme and .alpha.Gal epitopes on glycosylated lipids and proteins of the cell surface are then labeled via an antibody composition which recognizes and binds the .alpha.Gal epitopes on the cell surface. Cells labeled with the anti-.alpha.Gal antibody can be isolated by sorting via fluorescence activated cell sorting (FACS), or by magnetic panning techniques. This method is suitable for the rapid positive or negative selection of .alpha.Gal-positive cells from within a population of .alpha.Gal-negative cells without the need to expose cells to antibiotics for any period of time. In addition, the specification provides a method for the production and purification of anti-.alpha.Gal antibodies from chicken egg yolk.