Suppression of the frequencies of sister chromatid exchanges in Bloom's syndrome fibroblasts by co-cultivation with Chinese hamster cells.

The effect of co-cultivation of Bloom's syndrome fibroblasts with Chinese hamster ovary cells (CHO) on the incidence of sister chromatid exchanges (SCEs) was studied. The results show that suppression of the frequency of SCEs in Bloom's syndrome cells occurs only if cell to cell contact is present with CHO cells, without any effect on the SCE frequency in the latter. It is suggested that possible genetic heterogeneity between different Bloom's syndrome patients can be studied using the method of co-cultivation.