Increased sensitivity of a xeroderma pigmentosum lymphoblastoid cell line to serum deprivation in vitro

Two human lymphoblastoid cell lines, GM 1989, from a normal individual, and GM 2345, from a patient with xeroderma pigmentosum, complementation group A, were selected for comparative biochemical studies because they both grow rapidly and at virtually identical rates in sealed flasks in RPMI 1640 medium buffered to physiological pH with HEPES buffer, supplemented with 12% heat-inactivated fetal bovine serum. Although the two cell lines showed no difference in growth parameters assayed by standard methods, further studies showed that the GM 2345 cell line was markedly more sensitive to diminution of the serum concentration of the culture medium than was the normal cell line. These results indicate that lymphoblastoid cell lines, particularly those from individuals with certain genetic or metabolic diseases, may be growing under marginal or limiting circumstances, different from those of control cell lines, which are not detected by standard techniques used to monitor mammalian cell cultures.