CD4 and CD8 lymphocytes

HIV, Western blot, CD4 and CD8 lymphocytes
HIV is a virus discovered and identified in 1982; it originated on the shores of Lake Tanganyika in Africa and appears to be an animal virus that adapted to humans. This virus causes AIDS (acquired immunodeficiency syndrome), a serious infection that first emerged in the early 1980s, when it affected the gay communities of New York and Miami. From then on, outbreaks spread all over the world. The disease is called a “syndrome” because it is an infection that causes many manifestations, as the person becomes progressively immunocompromised (i.e. develops more infections, tumours, severe malaise and weight loss).
The main tests for diagnosing HIV are:

• Testing for anti-HIV antibodies
• The confirmatory or Western blot test
• Molecular biology tests
• CD4 (“helper”) and CD8 (“suppressor”) lymphocyte counts.

What they mean
Anti-HIV antibodies:
this is a screening test that does not, however, cover the “window period” (which lasts from 15 days to 6 months), because antibodies are not yet present at this stage.
• If the result is “present” or “positive”, the person has come into contact with the virus but may not have developed the disease.
For this reason it is advisable to carry out the confirmatory (Western blot) test.

Confirmatory or Western blot test:
• If the result is “present” or “positive”, the person has the infection and is therefore infected and infectious. This test not only confirms HIV positivity but also separates the various types of antibodies present, which is very important for deciding on treatment and for an overall picture of how the disease is progressing.

Molecular biology tests:
• If the result is “present” or “positive”, the person has come into contact with the virus; the importance of this test is that it detects HIV even during the “window period”. CD4 and CD8 lymphocyte counts: this test is useful to check that their balance in the blood is maintained (they represent a person’s immune system: CD4 cells help produce antibodies when they recognise a foreign agent, and CD8 cells complete the defensive action once the threat has been defeated), and in particular to monitor the effectiveness of treatment. If CD4 (“helper”) lymphocytes fall, the virus is destroying them and gaining ground.