Antibody penetration into living cells. IV. Different effects of anti-native DNA and anti-ribonucleoprotein IgG on the cell cycle of activated T gamma cells.

Normal T cells bearing receptors for the Fc portion of IgG that were incubated in anti-RNP or anti-DNA at the time of activation with phytohaemagglutinin showed different effects on this activation as determined by flow cytometric analysis of acridine orange stained cells. Incubation in anti-RNP caused an arrest in the progression from the G0 + G1 to the S + G2 phases of the cell cycle. Incubation in anti-native DNA caused activated cells to have an increase in their RNA content without a concomitant increase in their DNA content (DNA block). These effects were not seen in T cells that were depleted of T gamma cells by means of their property of forming rosettes with high affinity for sheep erythrocytes. Use of F(ab')2 fragments of either autoantibody, pre-incubation with aggregated IgG, or incubation with the respective autoantibodies in the cold effectively prevented their effect on the nucleic acid content of T gamma cells. Despite their different effect on the cell cycle both antibodies caused similar increase of 51Cr release of low affinity T cells 6 h after incubation in them. Our findings show that different anti-nuclear antibodies seem to cause different effects upon the cells they penetrate. These differences may have pathogenetic significance in the diseases where these antibodies occur.