A hypothesis implicating adhesive interaction specificities in the configuration of the mode of exponential growth of acute myeloid leukemia cells.

A hypothesis is presented which implicates cell-cell adhesive interaction specificities in the configuration of the mode of exponential growth of acute myeloid leukemia cells in vivo. An explosion growth of the leukemic clone maintains a 1:1 ratio between proliferating and nonproliferating leukemic blasts, thus, a proliferative index (f) value of 0.5. The proposed mechanism of proliferation control is based on the expression in competent leukemic blasts (cells with capacity to proliferate) of two membrane heterodimers, of the type Ra-Li and Ri-La ("R" and "L" standing for "receptor" and "ligand" and "a" and "i", for "activation" and "inhibition", respectively). Receptor occupation and/or the resulting signal transduction is mutually exclusive between Ra and Ri on the same cell. Between cells of an interacting pair, however, intercellular contact establishing interaction of these heterodimers (through 1Ra<--2La and/or 2Ri<--1Li, numbers denoting the different cells) imposes the limitation necessary to convey, in reciprocally opposite manner, signals for activation and inhibition of the cell's proliferative activity.