What is Leukocyte Adhesion Deficiency testing? Leukocytes, one of the essential cells involved in tissue repair, are an integral part of the immune system. Leukocytes activate the adaptive immune response by secreting pro-inflammatory cytokines and by way of phagocytosis; the balance between pro- and anti-inflammatory extracellular mediators is up regulated in responses to an array of pathogenic stimuli. The first work to link pro-inflammatory molecules from the EGF family to tissue repair in vivo was by the famous study group at Harvard Medical School where they analyzed patterns of leukocyte adhesion during repair in vivo in the context of leukocyte activation alone or in combination with other factors, which were believed to have important and central biomedical importance. The authors (Kam, Ilan and Oreshkar) started this technique with the idea that leukocytes do not reach the site of normal activation but rather become activated bone marrow microenvironment (BME) through interactions with specific molecules, either neutrophil receptor activator of nuclear factor kappa-light-chain-enhancer of activated B (eN&P) and various interleukins. The main focus of the method is to look at specific molecules during leukocyte adhesion itself, and not all inflammatory molecules can be separated from their ligands by using the same binding approach. A sample of leukocyte adhesion can be shown in Figure 1a with this sampling approach. In the same way that cells express the phagocytosis receptors P21 and T or B220 for the recognition of activated lymphocytes, the molecules they contain in the peripheral lymphatic system (LPS) for binding or transporting pro-tumor inflammatory cells are T and B cells (B cells) for binding, while LPS for release. The authors did not find any relationship between leukocyte adhesion molecules (pro-proinflammatory molecule), T, B cell receptors (B220) and leukocyte activation (leukocyte activation). This study proves the principle of leukocyte ligand production by a model system of leukocyte activation, which is much more informative than single molecule studies since cell binding and transport is not directly monitored at timepoint or condition. Figure 1a sample of murine leukocytes adhesion showing specific molecules: P3, P21, CD39AM, p27, ICAM1, VLA-4, TIMP1.](physnames-25-147-g001){#F1} 
