A new multi-well assembly was used for the in vitro chemotaxis assay of human peripheral blood monocytes. N-formylmethionyl-leucyl-phenylalanine caused concentration-dependent migration of the monocyte into the lower surface of the metal flamed membrane filter. Measurement was performed by the microplate reader (550-600 nm), and the absorbance showed the complete dependence on the number of migrated cells.
