Some immunochemical properties of Le(a)-and Le(b) -active substances in human urine.

Le(a)- and Le(b)-active substances present in normal human urine were isolated by sequential membrane filtration, column chromatography with DEAE-Sephadex (A-25), and gel filtration of Bio-Gel (P-6). Le(a)-active substance with the highest activity was obtained in the P-1 fraction (0-8 mg/1) from urine of a non-secretor type by the final gel filtration. Le(b)-active substance with the highest activity was also obtained in the P-1 fraction (0-2 mg/1) from urine of a secretor type. The P-1 of the non-secretor inhibited Le(a)-anti-Le(a) haemagglutination minimally at 4 microgram/ml, and the P-1 of the secretor inhibited Le(b)-anti-Le(b) haemagglutination at 1 microgram/ml. Both P-1 fractions possessing Le(a) or Le(b) activity were characteristic in having a much higher focuse content than other isolated fractions, and seemed to be complex carbohydrates with molecular weights of the order of 4-5 x 10(3).