Elucidation of the different effects of polyamines and other naturally-occurring inhibitors of cell proliferation (chalones) on T-lymphocyte and granulocyte colony growth in vitro.

Using T-lymphocyte and granulocyte colony assays with truly proliferating cells the effects of the polyamine spermine and of other naturally-occurring inhibitors of cell proliferation have been differentiated. It has been confirmed that spermine, in the presence of fetal calf serum, is a potent inhibitor of cell proliferation. This inhibition could be reversed by the addition of either 3-hydroxybenzyl-oxyamine or 4-bromo-3-hydroxybenzyl-oxyamine, both of which are inhibitors of the polyamine oxidase. In comparison, fractions isolated from calf thymus were shown to inhibit lymphocyte, but not granulocyte colony growth, indicating their tissue specificity and lymphocyte chalone activity. Further this inhibition was not reversed by polyamine oxidase inhibitors demonstrating that polyamines were not the inhibitory principles in this preparation.