New placental proteins and their potential diagnostic significance as tumour markers

Five new soluble placental tissue proteins (PP8, PP9,, PP10, PP11 and PP12) have been isolated, purified and characterized. PP, has the electrophoretic mobility of a beta 1-globulin; the other 4 proteins are alpha 1-globulins. The molecular weights of these proteins range from 25 000--65 000 daltons. They all are glycoproteins with carbohydrate contents ranging from 3.9--6.6%. The amino acid compositions of these proteins also have been determined. PP8 and PP, are ubiquitous tissue proteins in that they occur in relatively high concentrations in almost all human tissues examined. PP10, PP11 and PP12 could not be detected in extracts of other human tissues and, therefore, were supposed to be specific to the placenta. PP10--12 was shown to be present in tumour tissues by an immunoglobulin enzyme bridge (PAP) technique. The results suggest that these proteins may be useful as markers in oncology.