Leucocyte alloantigens as markers on cultured human cells

Abstract

R ECENT studies have shown that tissue culture cell lines are frequently contaminated with cells from a species other than that from which the cell line was thought to be derived [l, 5, 7, 8, lo]. The most commonly detected contamination is of animal cell lines by human cells, but it is also possible that one human cell line may be contaminated by cells from another human cell line. This contamination could not, of course, be detected using species specific antisera. In order to detect such contamination, and as a necessary prerequisite for the study of antigen synthesis and of genetic change in human cells, a search for alloantigens2 on cultured human cells has been initiated. Chalmers ef al. [3] observed that leucocyte alloantibodies can be shown (by the mixed antiglobulin reaction), to react with HeLa cells and it has now been found that, with certain sera, mixed agglutination between cultured human cells and human leucocytes can be produced (Fig. 1). The mixed agglutination reaction requires the presence of the same antigen on both tissue culture cell and on the indicator cell (leucocytes) which are linked together by suitable antibody and is therefore better suited to the analysis of the antigens of cultured human cells than systems like the mixed antiglobulin reaction [3] which detect only the combination of antibody with tissue cell. This report describes preliminary investigations on several human cell lines, the characteristics of which are given in Table I. The results of mixed agglutination tests on these cell lines using human leucocytes obtained from blood group 0 persons and fixed with formalin are shown in Table I. The antiserum used in the experiments summarized in this Table was obtained from a multiparous woman, and contains alloantibodies of many different specificities, as yet unanalysed. The techniques of preparing the indicator leucocytes and of performing the mixed agglutination reaction have been described elsewhere [3, 51. From Table II it may be seen that there is considerable antigenic diversity between cell lines, and that different HeLa cell lines show different patterns of cross reactions with indicator leucocytes. This serum does not react with a continuous rhesus monkey line (EMK IO I), with either primary or continuous vervet cell cultures or with a primary culture of puppy kidney cells, although there is some reaction with a primary rhesus monkey cell culture. These results suggest that leucocyte alloantigens may be used in the identification of human cell lines, and in distinguishing between different human cell lines, but further antigenic analysis of the sera used is obviously needed before any conclusions may be drawn about the relationships between different cell lines,