Cytoplasmic microtubules in polymorphonuclear leukocytes: Effects of chemotactic stimulation and colchicine

Indirect immunofluorescent (IIF) techniques employing antitutulin and anticentrosome antibodies were modified for studies of migrating polymorphonuclear (PMNs) leukocytes exposed to gradients or uniform concentrations of chemotactic factor (CF). No significant changes in microtubule (MT) number per cell occurred with chemotactic activation. Significant increases in average MT length per cell occurred upon exposure to gradients or uniform concentrations of CFs. Elongation of MT parallel to the direction of cell migration occurred coincident with shortening of other sets of MTs perpendicular to the direction of cell migration. MT extended radially from a single microtubule organizing center (MTOC) in >99.9% of cells. Following chemotactic activation, the location of the MTOC was observed between nuclear lobes in 65% of fully polarized cells, “posterior” to the nucleus in ⋍34% and “anterior” in less than 1%. Thus alterations of MT array occur coincident with cell orientation or migration in response to chemotactic stimuli.