Article Abstract:
The absence of alpha-4 integrins produces a lymphocyte-specific defect in hematopoiesis in the bone marrow. Alpha-4 integrins are unnecessary during embryonic lymphocyte development. However, T cells become alpha-4 integrin-dependent after birth. Monocytes and natural killer cells develop without the presence of alpha-4 integrins while precursors for T and B cells need the integrins. Alpha-4 integrins are essential for lymphocyte homing to Peyer's patches but unnecessary for other secondary lymphoid organs, such as spleen and intestinal epithelium.
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Article Abstract:
The important role of alphav integrins in many developmental processes is analyzed. A study was conducted on mice by eliminating their alphav integrin gene. While the experiment involved lethality, results showed that the removal of all five alphav integrins permits substantial and normal development and organogenesis as well as angiogenesis and particularly, vasculogenesis. These findings suggest a reevaluation of the genetic importance of integrins.
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Article Abstract:
The phenotype of mice without endothelial selectins after sequential ablation of the genes encoding P- and E-selectins is discussed. Said mice have severe leukocytosis, increased amounts of cytokine and changes in hematopoiesis. Granulocytopoiesis is enhanced both in bone marrow and spleen while erythropoiesis is partly transferred to the spleen. Findings indicate that endothelial selectins are important in leukocyte homeostasis.
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