T cells and HIV-induced T cell syncytia exhibit the same motility cycle.

Ameboid cells ranging in complexity from Dictyostelium amebas to human polymorphonuclear leukocytes (PMNs) translocate in a cyclical fashion. Using computer-assisted motion analysis, we have analyzed the motility of human lymphocytes of the immortal SupT1 cell line and of a peripheral blood mononuclear cell population highly enriched for CD4-positive cells (CD4-enriched PBMCs) on four substrates--plastic, dehydrated rat tail collagen, hydrated rat tail collagen, and bovine aortic endothelium. In addition, we have analyzed the motility on these substrates of syncytia induced by human immunodeficiency virus (HIV) in cultures of both cell types. It is demonstrated that both SupT1 cells and CD4-enriched PBMCs exhibit a motility cycle with a period of 1.6 min that is independent of substrate, independent of average cell velocity, and similar to the periods of translocating Dictyostelium amebas and PMNs. More surprisingly, it is demonstrated that HIV-induced SupT1 and PBMC syncytia with volumes 10 to 100 times those of single cells exhibit the same motility cycle as their single-cell progenitors. These observations support the generality of the motility cycle in animal cells and, for the first time, demonstrate that the cycle is independent of cell size.