Cluster formation in PHA-stimulated mononuclear cells from peripheral blood: effects of colcemid and taxol

Mononuclear cells from peripheral blood were incubated with phytohemagglutinin (PHA) for 24-72 hours. The cells formed dense cell clusters with firm cell-to-cell attachment and signs of cell communication, proliferation and differentiation. At the end of a 72-hour period of incubation, the test preparations were treated for 90 minutes with the classical microtubule antagonist Colcemid and the new microtubule antagonist taxol. Taxol produced approximately twice as many mitoses as Colcemid. Chromosomes in taxol-blocked mitoses appeared to be more contracted than chromosomes in Colcemid-blocked mitoses. It is suggested that one beneficial side effect of Colcemid preparation of chromosomes is stretching due to microtubule disassembly.