EXTERNAL CALCIUM-DEPENDENT, F-ACTIN-INDEPENDENT AND PERTUSSIS TOXIN-INSENSITIVE NOVEL NEUTROPHIL LOCOMOTION INDUCED BY A MAB

We previously demonstrated that a mAb to human neutrophils, designated 3H9, which was established by screening for inhibition of neutrophil adherence to plastic plates containing fetal bovine serum, enhanced bo th n-formyl-methionyl-leucyl-phenylalanine (FMLP)-induced chemotaxis a nd random migration of neutrophils, In the present study, we examined the mechanisms of 3H9-induced enhancement of neutrophil locomotion in the phagokinetic track assay. 3H9-induced neutrophil locomotion mainta ined a straight path which was different from the track resulting from FMLP-stimulated locomotion, This 3H9-induced migration required extra cellular Ca2+. beta(2)-Integrin activation was a prerequisite far the increase in cytosolic free calcium induced by 3H9 treatment. However, stimulation by 3H9 did not induce an increase in F-actin, even after C D18 activation. Signal transduction after molecular recognition by 3H9 was not mediated by pertussis toxin-sensitive, heterotrimeric G prote ins, These results suggest that 3H9 enhances neutrophil migration by m echanisms which are different from those involved in usual chemoattrac tant-induced migration. Neutrophil surface molecules recognized by 3H9 may play a crucial role in the regulation of transendothelial migrati on of leukocytes.