Chromosome analysis of five longterm cell culture populations derived from non-leukemic human peripheral blood (Detroit strains).

Abstract

Summary 1.Chromosome counts of five stable epitheliallike cell strains derived from normal human peripheral blood all showed pronounced heteroploidy. The stem-line number in blood lines -B16, -B17, -B96, and -B110 was 65. Blood line -B78 had its s -mode at 80. The majority of cells in strain -B17 existed in the 2 s range, having a mode of 120. The 120 mode in strain -B17 may actually represent the functional stem line of this strain. 2.Determination of the relative number of cells in the s and 2 s condition showed that in the strains -B16, -B96, and -B110 approximately 75 per cent of the cells were in the s condition and approximately 25 per cent in the 2 s condition. Strain -B78 had 97 per cent in the s condition and 2 per cent in the 2 s condition, while strain -B17 had 6 per cent in the s condition and 90 per cent in the 2 s condition. These relationships correlated with observations of nuclear size in cell sheet preparations. 3.Indirect evidence was given for true variation in chromosome number within the s complement and autonomy of the 2 s component with respect to the s component. 4.Studies on chromosome morphology indicated no significant difference between strains on the basis of morphological types as determined by arm length ratios. Distributions of morphological types in accumulated data of all the cell strains showed 53 per cent medical chromosomes, 32 per cent submedial chromosomes, and 17 per cent subterminal and terminal chromosomes. It was uncertain that morphological differences existed between the Detroit blood lines and chromosomes of the normal human karyotype. 5.The significance of the findings with respect to current hypotheses concerning the development of stable heteroploid in vitro cells trains from human sources was discussed. It is speculated that heteroploid cells may develop from tetraploid cells by a mechanism of mutation and selection.