Dendritic cell migration in different micropore filter assays.

Dendritic cells (DC) are highly motile and have been shown to migrate in vitro or in vivo towards various chemoattractants. Micropore filter methods with polycarbonate filters are generally used in these in vitro experiments. Among others, the main drawback of these filters is their thickness, which does not allow any assessment of effects of absolute concentration compared to gradients. The aim of this study was to establish a chemotaxis assay for dendritic cells using nitrocellulose filters, which can be adapted for checkerboard studies to distinguish between chemokinesis and chemotaxis. Immature DC were generated by culture of peripheral blood mononuclear cells using granulocyte-macrophage colony-stimulating factor and interleukin-4. We tested cell migration into nitrocellulose in a Boyden microchemotaxis chamber (leading front assay) and compared this method to the commonly used polycarbonate filter technique. Dendritic cells migrated well into nitrocellulose towards gradients of formyl peptide, complement fragment 5a, and monocyte chemotactic protein-3. The nitrocellulose method appeared to be more sensitive as compared to experiments testing migration across polycarbonate filters. Subsequent checkerboard analyses confirmed chemotactic activities of formyl peptide and complement fragment 5a. However, depending on the assay system, chemotaxis in polycarbonate filters but chemokinesis in nitrocellulose filters were observed for monocyte chemotactic protein-3. Measurement of DC migration in a cellulose nitrate micropore filter assay is more sensitive than the commonly used polycarbonate method and can be adapted for checkerboard analyses.