Human monocyte chemotaxis in vitro. Influence of in vitro variables in the filter assay.

Using a modified Boyden chamber technique, variables in the cell environment were investigated and found to have a profound influence on the monocyte chemotactic responsiveness. The concentration of monocytes, pH of cell suspension, the presence of protein, the concentration and pH of cytotaxins, time allowed for migration and the temperature were all found to be critical factors for the migration response. Optimal concentrations of casein, zymosan-activated serum and N-f-methionyl-leucyl phenylalanine had equal cytotactic potency. The addition of gentamycin decreased the monocyte chemotactic responsiveness, while penicillin had no effect. Under standardized conditions the technical variability was moderate and the intra-individual variability in healthy donors was continuously less than twenty per cent.