82. Which one of the following laboratory tests would be the best to determine the number of CD4-
positive cells in the blood of a patient infected with HIV?
1. Agglutination
2. Complement fixation
3. Flow cytometry
4. ELISPOT

 

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Determining CD4-Positive Cells in HIV Patients

The number of CD4-positive cells in a patient’s blood is a critical indicator of immune function, especially for patients infected with HIV. Monitoring the levels of these cells helps assess the progression of the disease and the effectiveness of treatments.

Why CD4-Positive Cells Matter in HIV

CD4-positive cells are a type of T lymphocyte that play a central role in the immune system by coordinating the immune response to infections. In HIV infection, the virus targets and destroys these cells, leading to a weakened immune system. Therefore, measuring the number of CD4-positive cells is essential for monitoring HIV progression.

Laboratory Tests for CD4-Positive Cells

When diagnosing and monitoring HIV, various laboratory tests can be used. However, some tests are more effective than others in determining the exact number of CD4-positive cells. Here are some common tests and their suitability for this purpose:

1. Agglutination

Agglutination tests involve the clumping of cells or particles, usually to detect the presence of antibodies or antigens. While useful for detecting the presence of specific pathogens, agglutination is not effective for determining the number of CD4-positive cells in the blood.

2. Complement Fixation

Complement fixation tests are used to detect the presence of specific antibodies by assessing the activation of the complement system. However, this test is not designed to count or identify specific immune cell types like CD4-positive cells.

3. Flow Cytometry

Flow cytometry is the most accurate and reliable method for counting CD4-positive cells in the blood. This technique uses fluorescently labeled antibodies to bind to specific markers on cell surfaces. By passing the cells through a laser beam, flow cytometry can quickly and accurately determine the number of CD4-positive cells, making it the gold standard for monitoring HIV patients.

4. ELISPOT

The ELISPOT (Enzyme-Linked ImmunoSpot) test is used to detect immune cell responses to specific antigens, such as cytokine production. While it can provide valuable information about immune function, it is not typically used for counting CD4-positive cells.

Answer: Option 3 – Flow Cytometry

The best laboratory test for determining the number of CD4-positive cells in the blood of a patient infected with HIV is flow cytometry. This method offers high accuracy and precision, making it the standard for monitoring the immune status of HIV patients.

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Conclusion

For HIV patients, monitoring CD4-positive cell counts is essential for assessing disease progression and treatment response. Among various laboratory tests, flow cytometry stands out as the most reliable and effective method for determining CD4 counts, providing crucial information for patient management.