Question

What is the significance of the CD4+ count in the pathophysiology of HIV?

Answer 1

CD4 lymphocytes or T helper cells are a subtype of T- cells and on their surfaces they can able to carry CD4+ membrane glycoprotein, so due to this reason thses are called as CD4 lymphocytes.

CD4 lymphocytes are T helper lymphocytes that present in their plasma membrane receptor proteins called CD4. These cells are crucial for defense against both extracellular and intracellular pathogens.

CD4 lymphocytes cell relationship with HIV and its replication:

CD4 lymphocytes are the cells that HIV infects and within which the virus replicates. HIV has proteins in its capsule that bind to the CD4 receptors of lymphocytes. Through that bond the virus fuses with the cell membrane and its content (RNA, reverse transcriptase, protease, etc.) penetrates into the cytoplasm and the viral replication process begins.

HIV RNA is then converted into DNA by the reverse transcriptase. The new DNA is inserted into the genetic material of the lymphocyte with the aid of enzymes called integrates. By transcription and translation this DNA commands the synthesis of proteins necessary for the assemblage of new viruses. Long polypeptides are thus produced and then fragmented into proteins and viral enzymes by the enzyme protease. So new HIV viruses are assembled and break the cell membrane to gain the circulation.

CD4 count:

The CD4 count tells how your immune system is functioning. CD4 cells are white blood cells that fight infection. The more you have, the better. These are the cells that the HIV virus kills. As HIV infection progresses, the number of these cells declines. When the CD4 count drops below 200 due to advanced HIV disease, a person is diagnosed with AIDS. A normal range for CD4 cells is about 500-1,500. Usually, the CD4 cell count increases as the HIV virus is controlled with effective HIV treatment. The higher your CD4 count, the better.