The response of a variety of human fibroblast cell strains to the lethal effects of alkylating agents.

The sensitivities of fifteen human fibroblast cell strains to the lethal effects of alkylation damage produced by N-methyl-N-nitrosourea (MNU) and N-ethyl-N-nitrosourea (ENU) have been investigated. Nine cell strains were also investigated for their sensitivities to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Included in our survey are representative strains derived from donors with the repair defective syndromes xeroderma pigmentosum (XP) and ataxia-telangiectasia (A-T), as well as strains derived from patients with Cockayne's syndrome, Bloom's syndrome, Huntington's disease and strains derived from individuals with unclassified syndromes. On the basis of our survival data we report that hypersensitivity to MNU is shown by two A-T strains (AT3BI and AT5BI), an XP strain (XP3BR), and strain 46BR derived from a patient with hypogammaglobulinaemia. This sensitivity to methylating agents is also shown by strains 46BR and XP3BR when treated with MNNG, but not for strain AT5BI. Sensitivity to ENU is shown by strain 11961 (derived from a sun-sensitive individual), XP3BR and a single Cockayne's syndrome strain CS697CTO. Of the strains studied only XP3BR was sensitive to both ethylating and methylating agents and only 46BR showed a greater than two-fold increase in sensitivity compared to normal.