Pathological inflammation, such as occurs in allergic contact dermatitis and delayed-type hypersensitivity, requires migration into the inflamed region of lymphocytes and granulocytes, as well as dendritic cells (DCs) and other antigen-presenting cells (APCs). Adhesive interactions of these migratory cells with the vascular endothelium and with other cell types and extracellular macromolecules must therefore be tightly regulated . The integrin b2 subunit, also called CD18, is found in several heterodimeric forms that are expressed by myeloid cells and is central to many of these interactions. The importance of CD18 in host defense is evident because patients with leukocyte adhesion deficiency type I (LAD I), who carry mutations in the corresponding human gene, are prone to bacterial infection. Grabbe et al. now report that in a mouse knockout model lacking CD18 entirely, animals are unable to mount the usual inflammatory responses to allergens. At the cellular level, the defect is specific for the extravasation of T cells, since APCs migrate normally into areas exposed to allergen. These findings generally confirm cell culture and intravital microscopic studies indicating that b1 integrins can substitute for b2 in monocytes and DCs but not in lymphocytes. Interestingly, CD18-deficient T cells appear to be spontaneously hyperactivated, suggesting that adhesion through CD18 helps suppress autoimmune activation.

'"/>

Contact: John Ashkenas
scied@the-jci.org
416-946-7593
Journal of Clinical Investigation
16-Jan-2002

Page: 1
Related biology news :

1. Adhesive science can help optimize use of timber resources
2. New technique helps scientists reveal interactions between genes and drugs
3. A pregnant pause for unexpected interactions
4. Butterflies & the hormonal basis of interactions between life histories & morphology
5. Gene interactions control circadian clock in plants, study finds
6. Invariant properties in coevolutionary networks of plant-animal interactions
7. Algorithm predicts interactions between proteins whose structures are unsolved
8. Weizmann Institute scientists win global competition in predicting protein-protein interactions
9. Study offers a rare view of how species interactions evolve
10. Scripps scientists find ignored species play key role in ecosystem interactions
11. Cell interactions in spermatocyte apoptosis