Variation in expression of S₃ antigen in human sarcoma cell lines: Influence of passages and medium on generation of S₃

An antigen S₃, common to human sarcomas, has been detected by complement-fixation methods in sarcoma cell cultures (JNCI 57:489, 1976). Initial observations suggested that S₃ was present only during passages 1-3 and uniformly absent in older cell lines. This study was undertaken to determine the constancy of expression of S₃ in repeated passages in S₃-bearing cell lines. In addition, the influence of trypsinization and feeding on S₃ production were studied. Cell cultures prepared from 2 fibrosarcomas and chondrosarcoma were studied indetail in this regard. At each passage a sample was taken for cytological examination and another to determine whether S₃ was present. Expression of S₃ antigen was found to be extremely variable and no change in the distribution of cell types, morphologically identified, was noted, regardless of culture conditions and passage. The study confirms that S₃ antigen is most consistently expressed in early passages of human sarcoma cell lines and that this antigen may reappear in passages even if absent for as long as 4 serial passages. The variability of antigen production cannot be attributed to details of the trypsinization procedures used, the presence or absence of cell products in the medium used, or to the selection of specific cell types in the culture with the passage of time.