Radioimmunoassay of aldolase A. Determination of normal serum levels and increased serum concentration in cancer patients.

A radioimmunoassay specific for human aldolase A subunits was used to measure human aldolase A (ALD-A) in human serum. The double antibody competitive inhibition radioimmunoassay technique used radioiodinated purified ALD-A as ligand, chicken antisera specific for human ALD-A and rabbit antichicken IgG. The serum levels of ALD-A in 42 normal healthy subjects ranged from 130 to 210 ng/ml (mean average, 171 +/- 39 ng/ml). In 177 hospitalized patients without cancer, muscle diseases, or hemolytic anemia, the ALD-A serum levels ranged from 125 to 220 ng/ml. In contrast, 82% of 260 patients with various types of malignancy had ALD-A serum concentrations above the normal range. The CEA levels increased only 44% of the sera of 80 patients with cancer of the digestive tract, whereas the ALD-A levels were increased in 86% of the patients. The AFP levels were greater than 100 ng/ml in only 70% of the sera of 33 liver cell carcinoma patients, whereas the ALD-A levels were increased in 94% of these sera. The measurement of serum ALD-A by radioimmunoassay may be a valuable adjunct in the clinical diagnosis of certain cancer patients.