Morphological, histochemical and chromosomal patterns of neuroblastoma parental and purine resistant lines.

Several neuroblastoma clones and the same clones adapted to proliferation in a medium containing 15 mug/ml of 8-azaguanine and 6-thioguanine are characterized with respect to their morphology, acetylcholinesterase activity, catecholamine content and chromosomal pattern. Interclonal as well as intraclonal heterogeneity was found for the cell parameters studied. A reduction in the number of catecholamine-containing cells was observed in the azaguanine and thioguanine resistant adrenergic (M1, N115) cells compared with their parental lines. An increase of choline acetyltransferase activity was found in the M5 cholinergic clone, and a decrease of the same activity in the S21 cholinergic line selected in the medium with the purine analogues. Furthermore, a striking change in the distribution of chromosomes and chromosomal markers appeared in the resistant cells of all clones.