A CD4 count is a measurement of the number of a particular type of white blood cells (lymphocytes),CD4 T-cells, that help fight infection. As such, it’s an important indicator of the strength of the immune system for people with HIV. Regular testing to evaluate CD4 is used to monitor the progression of infection, to help predict the likely outcome (or prognosis) of the disease, and to evaluate how well treatment is working.
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Improving a person’s CD4 count is a key goal ofantiretroviral therapy (ART), but even for those who are strictly compliant about taking their medication as prescribed, CD4 sometimes doesn’t improve.
A primary reason for this has to do with timing: The earlier ART is started, the more effective it’s likely to be.If you’ve recently tested positive for HIV infection, you’ll want to understand the importance of keeping tabs on your CD4 count and how beginning treatment as soon as possible can impact it.
Understanding the Numbers
CD4 countsare expressed as number of cells per cubic millileter (mL) of blood:Normal: Between 500 and 1,200 cells/mLWeakened immune system/possibleHIV infection:Between 250 and 500 cells/mLAIDS/high risk of life-threatening opportunistic infections: 200 or fewer cells/mL
CD4 countsare expressed as number of cells per cubic millileter (mL) of blood:
Barriers to CD4 Recovery
However, if this doesn’t occur, a couple of factors largely having to do with the timing of the start of medication may be to blame.
CD Nadir
One of these is theCD nadir,which refers to thelowest level to which a person’s CD4 count dropped before they began medication.
The CD4 nadir can help predict the likelihood of certain illnesses, such as HIV-associated brain disorders, as well as how robust the immune system will be after therapy has already begun.
In general, someone with a very low CD4 nadir (under 100 cells/millileter) will have a more difficult time restoring immune function than a person with moderate immune suppression (over 350 cells/millileter).
T-Cell Exhaustion
T-cell exhaustion is one of the consequences of severe or long-term infection. It means that the structure and genetic coding of the cells are altered at the molecular level.Over time, the T-cells lose their ability to function and prevent disease progression.
While T-cell exhaustion has been primarily associated withCD8 T-cells, CD4 T-cells can also be adversely affected.
Improving the CD4 Count
Even so,positive lifestyle choicescan have a significant impact on overall health. Regular exercise, a healthy diet, quitting smoking, and cutting alcohol consumption are all beneficial for people with HIV, even for those whose CD4 count hovers well below normal levels.
Routine testing of CD4 counts also is important:For newly diagnosed people, CD4 testing should be performed prior to starting ART, repeated three months after therapy begins, and every three to six months thereafter.For those who have been on ART for at least two years and have had sustained, undetectable viral loads, testing should take place every 12 months for those who have CD4 counts between 300 and 500 cells/millileter.For those with CD4 counts over 500 cells/millileter, CD4 monitoring is optional.
Routine testing of CD4 counts also is important:
If testing reveals an elevated viral load, or even persistent, low-level activity, it may indicate the development of HIV drug resistance. In such cases, further susceptibility testing can be initiated to indicate what new treatment regimen should be used.
Essential Guide to HIV Therapy
A Word From Verywell
There’s no doubt a diagnosis of HIV infection is scary but thanks to our understanding of how the virus works and how it can be stopped from replicating, the majority of people who are HIV-positive do not go on to develop AIDS.
This is especially true the sooner the virus is detected and treatment begins, which is why ART is now recommended at the time of diagnosis for all people with HIV. By starting treatment earlier rather than later, the chance of a full immune recovery is improved, as is the likelihood of achieving a normal, healthy life expectancy.
4 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Herout S, Mandorfer M, Breitenecker F, et al.Impact of early initiation of antiretroviral therapy in patients with acute HIV infection in Vienna, Austria.PLoS ONE. 2016;11(4):e0152910. doi:10.1371/journal.pone.0152910Vidya Vijayan KK, Karthigeyan KP, Tripathi SP, Hanna LE.Pathophysiology of CD4+ T-Cell depletion in HIV-1 and HIV-2 Infections.Front Immunol. 2017 May 23;8:580. doi:10.3389/fimmu.2017.00580Negredo E, Massanella M, Puig J, et al.Nadir cd4 t cell count as predictor and high cd4 t cell intrinsic apoptosis as final mechanism of poor cd4 t cell recovery in virologically suppressed HIV-infected patients: clinical implications.Clinical Infectious Diseases.2010;50(9):1300-1308. doi:10.1086/651689Crawford C, Angelosanto J, Kao C, et al.Molecular and transcriptional basis of cd4+ t cell dysfunction during chronic infection.Immunity.2014;40(2):289-302. doi:10.1016/j.immuni.2014.01.005
4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Herout S, Mandorfer M, Breitenecker F, et al.Impact of early initiation of antiretroviral therapy in patients with acute HIV infection in Vienna, Austria.PLoS ONE. 2016;11(4):e0152910. doi:10.1371/journal.pone.0152910Vidya Vijayan KK, Karthigeyan KP, Tripathi SP, Hanna LE.Pathophysiology of CD4+ T-Cell depletion in HIV-1 and HIV-2 Infections.Front Immunol. 2017 May 23;8:580. doi:10.3389/fimmu.2017.00580Negredo E, Massanella M, Puig J, et al.Nadir cd4 t cell count as predictor and high cd4 t cell intrinsic apoptosis as final mechanism of poor cd4 t cell recovery in virologically suppressed HIV-infected patients: clinical implications.Clinical Infectious Diseases.2010;50(9):1300-1308. doi:10.1086/651689Crawford C, Angelosanto J, Kao C, et al.Molecular and transcriptional basis of cd4+ t cell dysfunction during chronic infection.Immunity.2014;40(2):289-302. doi:10.1016/j.immuni.2014.01.005
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Herout S, Mandorfer M, Breitenecker F, et al.Impact of early initiation of antiretroviral therapy in patients with acute HIV infection in Vienna, Austria.PLoS ONE. 2016;11(4):e0152910. doi:10.1371/journal.pone.0152910Vidya Vijayan KK, Karthigeyan KP, Tripathi SP, Hanna LE.Pathophysiology of CD4+ T-Cell depletion in HIV-1 and HIV-2 Infections.Front Immunol. 2017 May 23;8:580. doi:10.3389/fimmu.2017.00580Negredo E, Massanella M, Puig J, et al.Nadir cd4 t cell count as predictor and high cd4 t cell intrinsic apoptosis as final mechanism of poor cd4 t cell recovery in virologically suppressed HIV-infected patients: clinical implications.Clinical Infectious Diseases.2010;50(9):1300-1308. doi:10.1086/651689Crawford C, Angelosanto J, Kao C, et al.Molecular and transcriptional basis of cd4+ t cell dysfunction during chronic infection.Immunity.2014;40(2):289-302. doi:10.1016/j.immuni.2014.01.005
Herout S, Mandorfer M, Breitenecker F, et al.Impact of early initiation of antiretroviral therapy in patients with acute HIV infection in Vienna, Austria.PLoS ONE. 2016;11(4):e0152910. doi:10.1371/journal.pone.0152910
Vidya Vijayan KK, Karthigeyan KP, Tripathi SP, Hanna LE.Pathophysiology of CD4+ T-Cell depletion in HIV-1 and HIV-2 Infections.Front Immunol. 2017 May 23;8:580. doi:
10.3389/fimmu.2017.00580
Negredo E, Massanella M, Puig J, et al.Nadir cd4 t cell count as predictor and high cd4 t cell intrinsic apoptosis as final mechanism of poor cd4 t cell recovery in virologically suppressed HIV-infected patients: clinical implications.Clinical Infectious Diseases.2010;50(9):1300-1308. doi:10.1086/651689
Crawford C, Angelosanto J, Kao C, et al.Molecular and transcriptional basis of cd4+ t cell dysfunction during chronic infection.Immunity.2014;40(2):289-302. doi:10.1016/j.immuni.2014.01.005
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