Neutrophil granulocyte chemotaxis in vitro. Comparison of the response to casein and a bacterial chemotactic factor, and evaluation of an automatic method for counting cells on a membrane filter surface.

A method is described for evaluating neutrophil granulocyte chemotaxis in vitro, using a modified reversible Boyden chamber. The variation in cell detachment from the attractant surface of the filter after the migration through the filter was shown to be eliminated by reversing the chambers during the incubation period. In unreversed chambers, the loss of cells from the bottom surface of the filter was much higher on attraction with casein than with a bacterial chemotactic factor (BCF). The finding of a different kinetic response to casein and to BCF may suggest differing affinity to various chemoattractants within circulating neutrophils. The results obtained after introducing an automatic quantitative image analysis system for the counting of the cells at the filter surface are found to be very well correlated to those with conventional direct microscope counting.