CD3 (immunology)

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CD3 (immunology)

File:CD3Complex.png
The CD3 complex is a group of proteins that serve as a co-receptor to aid in activating the T cell.

The CD3 (cluster of differentiation 3) is a complex of proteins that forms part of the T cell receptor (TCR) complex on the surface of T cells. It plays a crucial role in immunology, specifically in the activation and differentiation of T cells. The CD3 complex is composed of four distinct polypeptide chains (ε, γ, δ, and ζ), which are encoded by separate genes and have different functions.

Structure and Function[edit | edit source]

The CD3 complex is associated with the TCR, which recognizes antigens. The CD3 components are responsible for signal transduction upon antigen recognition. The CD3-ε, γ, and δ chains each have an immunoreceptor tyrosine-based activation motif (ITAM) in their cytoplasmic domain, while the ζ-chain has three ITAMs. Upon antigen recognition, these ITAMs are phosphorylated, initiating an intracellular signaling cascade that leads to T cell activation.

Role in Immune Response[edit | edit source]

The CD3 complex plays a vital role in the immune response. It is involved in the activation of T cells, which are essential for cell-mediated immunity. T cells recognize and respond to antigens, leading to the destruction of infected cells or the production of cytokines that regulate the immune response. The CD3 complex is crucial for this process, as it transmits the signal from the TCR to the inside of the cell, triggering the T cell's response.

Clinical Significance[edit | edit source]

Alterations in the CD3 complex can lead to various immune disorders. For example, mutations in the genes encoding the CD3 chains can result in severe combined immunodeficiency (SCID), a condition characterized by a severe defect in both the T and B lymphocyte systems. Additionally, the CD3 complex is a target for immunosuppressive drugs used in organ transplantation, such as muromonab-CD3, which binds to the CD3 complex and inhibits T cell activation.

See Also[edit | edit source]

References[edit | edit source]


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Contributors: Prab R. Tumpati, MD