INHIBITION OF MITOGEN-INDUCED CHANGES IN INTRACELLULAR FLUORESCEIN FLUORESCENCE POLARIZATION OF HUMAN PERIPHERAL-BLOOD LYMPHOCYTES BY COLCHICINE, VINBLASTINE AND CYTOCHALASIN-B

We have previously reported that the exposure of human peripheral bloo d lymphocytes (PBL) to a variety of stimulants caused rapid changes in intracellular fluorescein fluorescence polarization (IFFP) in the act ivated cells. In the present study we further analyzed possible mechan isms responsible for the changes in IFFP in PBL exposed to phytohaemag glutinin (PHA) and anti-CD3 antibody. By employing several agents whic h are known to affect the polymerization of the cytoskeleton we showed that both cytochalasin B, which regulates the microfilaments structur e, and vinblastine and colchicine, which affect the microtubules, comp letely abolished the changes induced in IFFP of human PBL by both PHA and anti-CD3. This effect was dose dependent and was noted at concentr ations ranging from 10 to 100 mu M of cytochalasin B and 10 mu M of vi nblastine and colchicine. The effect of these cytoskeleton modulators occurred within 20 minutes after the initiation of activation with PHA . Our results indicate that activation with PHA and anti-CD3 causes ea rly changes in the microtubules and microfilaments components of the c ytoskeleton. The possible application of IFFP measurement in analyzing early changes in the cytoskeleton following cell activation is discus sed.