Chromosome fragility in New Zealand black mice: effect of syngeneic, allogeneic, and xenogeneic sera on fetal fibroblasts in vitro.

The sensitivity of fetal fibroblasts from New Zealand Black (NZB) and BALB/c mice to syngeneic, allogenic, and xenogeneic sera was tested. The NZB fetal fibroblasts manifested significantly more chromosome abnormalities when grown in the presence of syngeneic sera or in one of three tested allogeneic sera but no in xenogeneic sera. In contrast, no chromosome fragility was observed in BALB/c fetal fibroblasts tested under similar conditions. These findings suggested that NZB fetal fibroblasts are not generally unstable but that the instability is expressed only in response to specific factors(s) present in syngeneic sera from young and old mice.