Helper T Cells (CD4 ) - Histology

What Are Helper T Cells (CD4)?

Helper T cells, also known as CD4 cells, are a type of lymphocyte that play a crucial role in the immune system. They are called CD4 cells because they express the CD4 glycoprotein on their surface. These cells are essential for orchestrating the immune response by activating and directing other immune cells.

Where Are Helper T Cells Found?

Helper T cells are primarily found in the lymphoid tissues such as the spleen, lymph nodes, and thymus. They circulate through the blood and lymphatic system, allowing them to interact with various antigens presented by antigen-presenting cells (APCs).

How Do Helper T Cells Develop?

The development of helper T cells occurs in the thymus. During maturation, T cell precursors undergo a selection process that ensures they can recognize self-MHC molecules but do not react strongly to self-antigens. This process involves both positive and negative selection, helping to prevent autoimmunity.

What Is the Role of CD4 in Immune Response?

CD4 cells are pivotal in initiating and regulating the immune response. Upon encountering an antigen-presenting cell displaying an antigen-MHC class II complex, CD4 cells become activated. They then differentiate into various subsets, such as Th1, Th2, Th17, and Treg cells, each producing different cytokines that influence the activity of other immune cells like B cells and cytotoxic T cells.

How Are Helper T Cells Identified in Histological Studies?

In histological studies, helper T cells can be identified using immunohistochemistry techniques that stain for the CD4 marker. Flow cytometry is another method used to quantify and analyze these cells in various tissues.

What Happens When Helper T Cells Are Dysfunctional?

Dysfunction in helper T cells can lead to compromised immune responses. For instance, in HIV/AIDS, the virus specifically targets and depletes CD4 cells, leading to immunodeficiency. Additionally, overactive or misdirected CD4 cells can contribute to autoimmune diseases such as rheumatoid arthritis and multiple sclerosis.

How Do Helper T Cells Interact with Other Immune Cells?

Helper T cells interact with other immune cells through direct cell-to-cell contact and by secreting cytokines. For instance, Th1 cells release interferon-gamma to activate macrophages, while Th2 cells secrete IL-4 and IL-5 to assist B cells in antibody production. Treg cells help maintain immune tolerance by producing IL-10 and TGF-beta.

Conclusion

Helper T cells (CD4) are indispensable for a functional immune system. Their ability to direct and regulate various immune responses underscores their importance in health and disease. Understanding their histological characteristics and interactions with other immune cells provides valuable insights into their role in maintaining immune homeostasis and combating infections.

Relevant Publications

The CCL2-CCR4 Axis Promotes Regulatory T Cell Trafficking to Canine Glioma Tissues.

Issue Release: 2024

The diagnostic value of selected immune parameters in peripheral blood of dogs with malignant mammary tumours - a preliminary study.

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Modifying T cell phenotypes using TYK2 inhibitor and its implications for the treatment of systemic lupus erythematosus.

Issue Release: 2024

In Situ Characterization of Human Follicular Helper CD4 T Cells.

Issue Release: 2024

Biomimetic gold nanocages incorporating copper-human serum albumin for tumor immunotherapy via cuproptosis-lactate regulation.

Issue Release: 2024

Deubiquitination of aryl hydrocarbon receptor (AhR) by USP21 negatively regulates Th17 cells differentiation.

Issue Release: 2024

Recognition of HIV-1-infected fibrocytes lacking Nef-mediated HLA-B downregulation by HIV-1-specific T cells.

Issue Release: 2024

Redefining Immune Dynamics in Acute Pancreatitis: The Protective Role of Galectin-3 Deletion and Treg Cell Enhancement.

Issue Release: 2024

Tumor microenvironment reprogramming improves nanomedicine-based chemo-immunotherapy in sarcomas.

Issue Release: 2024

DIAPH1-Deficiency is Associated with Major T, NK and ILC Defects in Humans.

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miR-16-5p specifically inhibits IFN-γ-regulated memory T helper cell differentiation in malignant pleural effusion of non-small cell lung cancer.

Issue Release: 2024

Identification and validation of genes associated with prognosis of cisplatin-resistant ovarian cancer.

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Anti-CTLA-4 treatment suppresses hepatocellular carcinoma growth through Th1-mediated cell cycle arrest and apoptosis.

Issue Release: 2024

Analysis of Immune Cell Subsets in Peripheral Blood from Patients with Engineered Stone Silica-Induced Lung Inflammation.

Issue Release: 2024

Conservation of HLA Spike Protein Epitopes Supports T Cell Cross-Protection in SARS-CoV-2 Vaccinated Individuals against the Potentially Zoonotic Coronavirus Khosta-2.

Issue Release: 2024

Inflammatory response in traumatic brain and spinal cord injury: The role of XCL1-XCR1 axis and T cells.

Issue Release: 2024

IL-2 amplifies quantitative TCR signalling inputs to drive Th1 and Th2 differentiation.

Issue Release: 2024

Nasally delivered chitosan-coated poly(lactide-co-glycolide) encapsulating honeybee venom enhances T helper 1-related immunity against Salmonella Typhimurium infection in pigs.

Issue Release: 2024

Discovery of Dual MER/AXL Kinase Inhibitors as Bifunctional Small Molecules for Inhibiting Tumor Growth and Enhancing Tumor Immune Microenvironment.

Issue Release: 2024

Alternative activation of mast cells by CD4+ T helper cells.

Issue Release: 2024

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