Inhibitory effect of guinea pig serum on JTC-11 cell growth in vitro

The growth of JTC-11 cell line which was established from Ehrlich ascites carcinoma in vitro was inhibited by the addition of 2 per cent guinea pig serum to the control medium composed of 10 per cent bovine serum, 0.4 per cent lactalbumin hydrolysate and saline D. The concentration of guinea pig serum could be reduced to 0.02 per cent (lOγ of guinea pig serum protein/ml) with positive result, but 0.002 per cent guinea pig serum did not inhibit the growth at all. The inhibitory effect was not abolished by heating at 56°C, 66°C, and 70°C for 30 min but it was completely lost by heating at 100°C for 30 min. The inhibitory factor was undialyzable, and was inactivated with the treatment of 1mM HgCl2- Morphologically, the cells exposed to guinea pig serum showed pycnotic changes of the nuclei, accompanied by the formation of fine vacuole-like particles in the cytoplasm. Electron microscopic study revealed poor development of endoplasmic reticulum. There were more multivesicular bodies and large vacuoles with amorphous content in the cytoplasm of the damaged cells. The DNA synthesis in these cells was remarkably disturbed by 2 per cent guinea pig serum.