Inflammatory Cell Trafficking

They are: an increased blood supply to the area, bringing leucocytes and serum molecules to the affected site; an increase in capillary permeability allowing exudation of the serum proteins (antibody, complement, kininogens etc) required to control infection; an increase in leucocyte migration in the tissue. There is a clear distinction between the cell traffic which occurs to lymphoid tissues and that which occurs into sites of inflammation. The types of cells, which are seen at sites of inflammation, their preponderance and their time of arrival, depend primarily on the nature of the antigenic challenge and on the site where the reactions occur. In general, neutrophils are the first cells into sites of acute inflammation caused by infection. They represent the major cell type for several days. From the first day onwards mononuclear phagocytes and activated lymphocytes start to arrive.

Experimental procedures for cell trafficking in inflammation mainly should involve tests for chemotaxis of macrophages and neutrophils as well as tests for phagocytosis. The first one is performed by using a semipermeable membrane by putting on one side of the membrane the factors that are mitogenic or antigenic and on the other side known number of macrophages or neutrophils. The measure of a number of cells moving across the semipermeable membrane would indicate the response of cells in terms of chemotaxis.

A test for phagocytosis is done by incubating macrophages and neutrophils in a serum containing medium to which known counts of Staphylococcus aureus are added and after some time percentage of viable organisms in the medium are calculated by bacterial count. This would give an assessment of phagocytosis and intracellular killing. Similarly by adding latex particles it is possible to assess the phagocytic activity of macrophages and neutrophils.