The chemotactic response of granulocytes to the low molecular weight chemoattractants f-MLP, C5f, and LTB4 is dependent on chemokinetic factors.

The dependence of the low molecular weight chemoattractants (LMCs) formylmethionyl-leucylphenylalanine (f-MLP), C5f, and leukotriene B4 (LTB4) on albumin to express their chemotactic activity towards granulocytes (PMNs) was investigated in order to study the required qualities of albumin and if albumin could be replaced by any other proteins. The results demonstrated that the supporting effect of isolated albumin was dependent on the method of purification. Only isolated albumin exposed to ethanol precipitation during the purification procedure supported the chemotactic effect of LMCs. The albumin preparation that supported the effect of LMCs also mediated a chemokinetic effect on PMN migration. Albumin isolated by methods other than ethanol precipitation neither exerted a chemokinetic effect nor supported the chemotactic effect of LMCs. Heated, normal serum and isolated alpha 1-antitrypsin supported the chemotactic activity of LMCs and also mediated a chemokinetic effect on PMN migration. The present investigation suggests an important role for the chemokinetic factors, since it is indicated that their presence is necessary for the chemotactic response of PMNs to the low molecular weight chemoattractants C5f; LTB4, and f-MLP.