Neutrophil chemotaxis: technical problems with nitrocellulose filters in Boyden-type chambers.

The chemotactic migration of murine polymorphonuclear neutrophils (PMN) in Boyden-type chambers was compared in Sartorius membranes which were untreated, or had been autoclaved, and which had been mounted in the chambers in alternative orientations. Migration was assessed by the leading front method. The PMN migrated significantly further in the untreated filters than in filters which had been autoclaved. The orientation of untreated filters in the chamber was critical: PMN migrated less far in filters which had been mounted in their original orientation in the shipping box than in filters which had been inverted before mounting.