Soluble tumor-associated markers in lung cancer extracts

Three lung tumor-associated markers (LTAM), previously identified as a Cohn Fraction IV α-globulin (LTAM-1), ferritin (LTAM-2) and lactoferrin (LTAM-3) were separated by a combination of ion exchange, dye-affinity and molecular sieve chromatography. They were further purified by polyacrylamide gel electrophoresis and antisera were raised. Analysis of human extracts by immunodiffusion showed that 80% of lung tumor extracts were positive for all three markers. Similarly, 70% of extracts from other tumors were positive for LTAM 1, but only 10% of these extracts were positive for LTAM 2 and 3. Variation in concentration of LTAM 2 and 3 among several extracts was determined by a quantitative enzyme immunoassay. Analysis of a select group of extracts for carcinoembryonic antigen (CEA), α-fetoprotein and β2-microglobulin showed 50% of these extracts to have markedly elevated levels of CEA. The results suggest that ferritin, lactoferrin and CEA offer promise as markers fo.