From the Guidelines
CD3 and CD4 cells are distinct components of the immune system, with CD3 cells being T lymphocytes that express the CD3 protein complex, and CD4 cells being a subset of T cells that express the CD4 protein and play a crucial role in coordinating immune responses. The primary function of CD3 cells is to recognize antigens presented by antigen-presenting cells, whereas CD4 cells, also known as helper T cells, release cytokines that activate other immune cells like B cells and cytotoxic T cells. CD4 cells are particularly important in fighting bacterial and fungal infections and are the primary targets of HIV, which is why CD4 counts are monitored in HIV patients 1. Key differences between CD3 and CD4 cells include:
- CD3 cells are a broader category of T lymphocytes, while CD4 cells are a specific subset of T cells
- CD3 cells recognize antigens, while CD4 cells coordinate immune responses
- CD4 cells are more susceptible to HIV infection, which is why CD4 counts are a critical marker of immune function in HIV patients 1. In clinical practice, CD4 cell counts are used to stage HIV disease, determine the need for prophylaxis against opportunistic infections, and monitor the response to antiretroviral therapy 1. Overall, understanding the distinct functions and characteristics of CD3 and CD4 cells is essential for effective immune system function and for managing HIV infection.
From the Research
CD3 and CD4 Cells
- CD3 is a marker for all T cells, while CD4 is a marker for a specific subset of T cells known as T helper cells 2.
- CD4 cells play a crucial role in the immune system, and their counts are used to monitor the health of HIV-infected individuals 3, 4, 5.
- CD3 cells, on the other hand, are a broader category of T cells that include both CD4 and CD8 cells 2.
Functions of CD4 and CD3 Cells
- CD4 cells help to coordinate the immune response by activating other immune cells, such as B cells and macrophages 6.
- CD3 cells, including CD4 and CD8 cells, work together to recognize and eliminate infected cells or foreign substances 2.
- The ratio of CD4 to CD8 cells can provide insight into the health of the immune system, with a lower ratio indicating immune suppression 2.
Clinical Significance of CD4 and CD3 Cell Counts
- CD4 cell counts are used to determine when to start antiretroviral therapy (ART) in HIV-infected individuals, although this is no longer the primary factor in deciding when to initiate treatment 3, 4, 5.
- CD4 cell counts can also be used to monitor the response to ART and to diagnose opportunistic infections 5.
- CD3 cell counts, including CD4 and CD8 cells, can provide a more comprehensive understanding of the immune system's function and can be used to diagnose a range of immune-related disorders 2.