Fusion of Erythrocytes and Other Cells with Retention of Erythrocyte Cytoplasm

Harris and his associates showed that when adult chicken erythrocytes were fused with actively dividing cells, the chicken crythrocyte nuclei in the resulting heterokaryons were activated and began to synthesize both DNA and R N A (1). In these experiments only the nucleus of the chicken erythrocyte was incorporated into the heterokaryon while the cytoplasm was lost by lysis (2, 3). Erythrocytes from 3 to 5-day chick embryos could be fused with other cells with retention of erythrocyte cytoplasm (4); but since the degree of inactivation of embryonic erythrocyte nuclei is uncertain, they seem to be unsuitable for nuclear activation studies. The present communication describes some of the properties of heterokaryons formed by fusing adult chicken and human erythrocytes with other cells, without loss of erythrocyte cytoplasm. These heterokaryons were formed with the aid of Sendal virus in the presence of bivalent metal ions (5-8). erythrocytes were obtained as described previously (6). Human blood, type O, aged 4-8 wk was used in experiments. The blood cells of each type were washed three times with solution K. The buffy layer containing white cells was discarded and the pellet was suspended in solution K to give a concentration of 5o/0 (vol/vol). Ehrlich ascites tumor cells were obtained as described previously (9) and suspended at a 10% (vol/vol) concentration in solution K. Cells of a subclone 3460-3B of a Syrian hamster melanoma cell line (10) were the generous gift of Drs. B. Ephrussi and M. C. Weiss (Centre de Gfinfitique Molficulaire, CNRS, 91, Gif-sur-Yvette, France). The cells were grown in glass T flasks containing F-10 med-