A fetuin‐like antigen from human nephroblastoma

Abstract

An antigen was detected in pooled human nephroblastomas using antiserum prepared in rabbits against an ethylenediaminetetra acetic acid (EDTA) extract of the tumors. This antigen was not found in normal human plasma or kidney extracts, and was not related to the ABO or Forssman blood groups. The antigen was detected in extracts of cultured nephroblastoma cells, but was not present in extracts of normal human fetal kidney cell cultures. The antigen is believed to be present at the cell surface, as cell viability was not significantly lowered during the extraction procedure. A reaction of complete identity was demonstrated by Ouchterlony double diffusion experiments with this antigen and purified bovine fetuin. The antigen was not found in extracts of human fetal spleen, thymus or kidney, nor in human fetal serum. Furthermore, the antigen does not possess determinants in common with the human alpha‐fetoprotein of hepatomas, nor was it detected in human renal clear cell carcinoma. Initial characterization of the antigen showed it to be nondialysable, not sedimentable at 100,000 × g for 2 h, stable to repeated freeze‐thawing and to incubation at 56° C for 1 h, and water soluble over a wide ph range. The antigen was susceptible to digestion with pronase and trypsin and possibly hyaluronidase, but not to ribonuclease or neuraminidase. The protein portion is therefore of major importance to the structural integrity of this antigen. The relationship between this antigen and other abnormal materials reported previously in nephroblastoma patients is being studied.