Leukocyte adherence assay

Biological activities of LTB4 are measured by che-motactic assay, granule enzyme release assay, superoxide generation, hamster cheek pouch vascular permeability assay, rat mesenteric venule leukocyte adherence and emigration assay, lymphocytes proliferation assay, and leukocyte adhesion assay. 

The method used to perform the chemotaxis assay on endothelial cells is essentially that previously described for neutrophils and leukocytes, with one major difference. With neutrophils the cells are placed in suspension in the upper well and the chemotactic agent is placed in the lower well. However, with endothelial cells, the cells are placed in suspension in the lower well, and the filter and upper well put in place. The apparatus is then inverted, and left in an incubator for 2-4 h to allow the cells to adhere to the filter. After this period of incubation, the chambers are inverted again, back to their original orientation. The medium in the upper well is then replaced with fresh medium containing the chemotaxin, and experiment is allowed to proceed. 

Adhesion molecules are a wide variety of molecules that can potentially be measured as a way of assessing the adherence of leukocytes and/or platelets or other adhesive proteins to the endothelial matrix. Some are receptors. Some of the examples include PECAM-1 (platelet-endothelial adhesion molecule 1), P-selectin, e-selectin, and VCAM-1 (vascular cell adhesion molecule i). At times, the receptor itself is measured but often it is a soluble portion that circulates that is the ligand. At present, there are no standardized assays and no reference interval studies or consistent assay validations. 

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