[Autogenous production of growth factor as a mechanism of the cellular multiplication of the lymphoblastoid line RPMI-6410t].

The cells of the lymphoblastoid strain, RPMI-6410t (from the blood of a patient suffering an acute myeloblast leukemia), were shown to synthesize constitutively and secrete into the culture medium a growth factor that maintains the reproduction of these cells. The 6410t cells were shown to bind specifically this factor and react to it by proliferation in the conditions of rarefied inoculation. The utilization of a medium conditioned by the 6410t cells provided almost 100% cloning of these cells when using the method of limiting dilutions in 96-well microplates at a density of one cell per well. The cloning of the 6410t cells without the conditioned medium with feeder cells (mouse splenocytes and peritoneal cells) failed. It is suggested that as a result of the second stage of malignant transformation the immortalized cell still requires an exogenous growth factor, unlike was considered earlier, but acquires the ability of producing an endogenous growth factor and, hence, escapes the environmental control.