Question

What are CD4 lymphocytes? What is the relationship between these cells and HIV? How does HIV replicate?

Answer 1

ANSWER:

HIV infection causes associate noninheritable immunological disorder, chiefly thanks to depletion of CD4 lymphocytes. The mechanism by that the virus depletes these cells, however, isn't clearly understood. Since the virus preponderantly infects CD4 lymphocytes in vivo, some have assumed that HIV replication directly kills the infected cells or that the anti-HIV immunologic response destroys them.

However, an oversized range of studies don't support this idea. Rather, the information powerfully indicate that CD4 white blood corpuscle depletion is by associateindirect mechanism. many theories on varied direct and indirect mechanisms square measure reviewed. the foremostplausible mechanism, that is backed by in vivo information, involves the results of HIV contact with resting CD4 lymphocytes, that cannot support virus replication.

HIV binding to, and sign through, CD4 and chemokine receptor molecules on resting CD4 lymphocytes and alternative cell varieties [which extensively happens because the rare, fruitfully infected cells (ie: infected cells manufacturing virus) migrate among alternative cells through the humourtissues into the blood] induces upregulation of L-selectin and Fas. once these resting, HIV-signaled CD4 cells come back to the blood, they home terribly speedily back to peripheral bodily fluid nodes and axial bone marrow, and their disappearance from the blood is probably going attributable to their departure the vascular system. around half of those cells that are induced by HIV to home to bodily fluid nodes square measure later induced into cell deaththroughout the method of trans-endothelial migration once secondary signals square measure received through varied orientating receptors.

These cells aren't creating HIV, which might explain the observation that CD4 cells not creating HIV square measure the predominant cells dying within the bodily fluid nodes of HIV+ subjects. These studies indicate that the principal mechanism of CD4 T-cell depletion by HIV is attributable to its use of CD4 as its primary receptor and therefore the sign induced through this receptor on nonpermissive (resting) T-lymphocytes. This distinctive mechanism of microorganism pathologic process, if correct, results in the chance that HIV may notcause depletion of CD4 lymphocytes if it used another receptor to infect CD4 lymphocytes.