Use of sparse-pore polycarbonate (Nuclepore) membrane for the measurement of chemotaxis of polymorphonuclear leukocytes. Comparison of 'micro-Boyden' chambers and estimation of 'drop-off' of cells.

Various modified Boyden chambers having upper and lower compartments of small volume ('micro-Boyden' chambers) were tested for their suitability for use with the recently described 'sparse-pore' polycarbonate (Nuclepore) membrane for the measurement of chemotaxis of polymorphonuclear leukocytes in vitro towards N-formyl-methionyl-leucyl-phenylalanine. Previously reported 'open-well' and 'blind-well' chambers, as well as a new chamber having a lower compartment made from perspex and an upper compartment made from silicone rubber were tested. The most satisfactory results were provided by the new chamber, and this is attributed to the easy, accurate filling of the lower compartment, the lack of distortion of membrane, and the reliability of the seals around the edges of the membrane which can be achieved with this chamber. Full humidification during assembly was necessary for obtaining maximal response of the cells through the 'sparse-pore' membrane in all types of micro-Boyden chamber. 'Drop-off' of polymorphonuclear leukocytes from the lower surface of the 'sparse-pore' membrane during incubation was also studied in these experiments and found to be slight.