RANDOM LOCOMOTION AND CHEMOTAXIS OF HUMAN BLOOD POLYMORPHONUCLEAR LEUKOCYTES (PMN) IN THE PRESENCE OF EDTA - PMN IN CLOSE QUARTERS REQUIRE NEITHER LEUKOCYTE INTEGRINS NOR EXTERNAL DIVALENT-CATIONS

Divalent cations are thought essential for motile function of leukocyt es in general, and for the function of critical adhesion molecules in particular, In the current study, under direct microscopic observation with concomitant time-lapse video recording, we examined the effects of 10 mM EDTA on locomotion of human blood polymorphonuclear leukocyte s (PMN), In very thin slide preparations, EDTA did not impair either r andom locomotion or chemotaxis; motile behavior appeared to benefit fr om the close approximation of slide and coverslip (''chimneying''). In preparations twice as thick, PMN in EDTA first exhibited active defor mability with little or no displacement, then rounded up and became mo tionless, However, on creation of a chemotactic gradient, the same cel ls were able to orient and make their way to the target, often, howeve r, losing momentarily their purchase on the substrate, In either of th ese preparations without EDTA, specific antibodies to beta 2 integrins did not prevent random locomotion or chemotaxis, even when we added a ntibodies to beta 1 and alpha v beta 3 integrins and to integrin-assoc iated protein, and none of these antibodies added anything to the effe cts of EDTA, In the more turbulent environment of even more media, eff ects of anti-beta 2 integrins became evident: PMN still could locomote but adhered to substrate largely by their uropods and by uropod-assoc iated filaments, We relate these findings to the reported independence from integrins of PMN in certain experimental and disease states, Mor eover, we suggest that PMN locomotion in close quarters is not only in tegrin-independent, but independent of external divalent cations as we ll.