Effect of passaging on Mer phenotype of human fetal cell cultures.

With increasing passage in culture, the human fibroblast cell strain GM11 lost the Mer+ phenotype (the ability to support the growth of adenovirus 5 damaged prior to infection by MNNG). All of 46 embryonic strains prepared either from various organs of 20 fetuses from 6-7 to 13-14 weeks of gestational age or from two hydatidiform moles showed normal repair of MNNG-treated virus. We conclude that human fetal strains are not usually deficient in such repair, and that the behavior of GM11 is atypical.