TCR Beta Chain Locus and Diversity Generation

Dendritic cells (DCs) are specialized antigen-presenting cells that capture antigens only through receptor-mediated endocytosis.

Upon maturation in secondary lymphoid organs, dendritic cells downregulate the expression of major histocompatibility complex (MHC) molecules.

Antigen-presenting cells (APCs) include macrophages and T cells.

Nucleated cells cannot display antigens on their surface via MHC class I molecules.

APCs, such as dendritic cells, are particularly efficient in antigen presentation due to their low expression of MHC molecules and co-stimulatory molecules.

Combinatorial diversity only refers to the random combination of V and J gene segments during gene rearrangement.

Junctional diversity is introduced by the precise joining of gene segments without any insertion or deletion of nucleotides.

The first checkpoint in lymphocyte maturation occurs in secondary lymphoid organs.

Auto-reactivity is a common event due to ineffective mechanisms of central and peripheral tolerance.

Peripheral tolerance involves the recognition of self-antigens by mature lymphocytes in secondary lymphoid organs.

Peptide binding to MHC molecules is influenced by the anchor amino acids within the peptide sequence.

During the Double-Positive (DP) stage, T cells express both CD4 and CD40 coreceptors.

Individuals always react the same way to identical peptides due to the uniform nature of MHC molecules.

Peptide fragments generated from endogenous proteins in the cytosol for display by class I MHC molecules are transported into the Golgi apparatus for binding.

Single-Positive (SP) stage involves negative selection for self-reactivity.

Antigen processing for display by class II MHC molecules occurs in the cytosol.

Antigen receptor gene rearrangement is not required for generating diverse repertoire of antigen receptors in T cells.

The diversity of the peptide repertoire generated from pathogens contributes to individual differences in immune responses.

The process of antigen receptor gene rearrangement involves the recombination of V, D, and J gene segments.

The Ig Heavy Chain Locus contains V, D, and C gene segments.

The interactions between the TCR and MHC-peptide complex primarily involve the constant regions of the TCR chains.

ITAM stands for Intracellular Tyrosine-based Activation Motif.

CD4 and CD8 are considered co-receptors because they directly phosphorylate ITAMs upon TCR engagement.

Lck (lymphocyte-specific protein tyrosine kinase) is responsible for modifying ITAM-containing proteins in a T cell.

HIV binds to CD8 as part of its entry mechanism into CD4+ T cells.

Costimulators are molecules expressed on the surface of T cells that provide additional signals to APCs to promote their activation and proliferation.

CD4 and CD8 are co-receptors that interact directly with MHC class II molecules, enhancing TCR-mediated antigen recognition.

CLTA-4 and PD-1 are costimulatory molecules expressed on the surface of APCs.

IL-2 plays a central role in antigen recognition and T cell activation.

Each T cell expresses receptors (TCRs) that are specific for multiple antigenic peptides presented by MHC molecules.

The pre-T cell receptor consists of a β chain and a surrogate α chain.

The association of CD3 signaling chains (ε, δ, γ) is required for activation and signaling in the pre-T cell.

In response to signaling from the pre-T cell receptor, the T cell undergoes apoptosis instead of proliferation and differentiation.

The generation of a large pool of T cells with identical antigen receptors occurs during negative selection in the thymus.

Effector T cells produced in the thymus express CD8 co-receptor.

T cell maturation involves positive selection for self-reactivity and negative selection for MHC recognition.

Costimulatory molecules, such as CTLA-4 and PD-1, promote T cell activation by inhibiting immune responses.

IL-2 is a cytokine that suppresses T cell proliferation and differentiation.

Peripheral tolerance involves the recognition of foreign antigens by mature lymphocytes in secondary lymphoid organs.

Junctional diversity is introduced by the random combination of V and J gene segments during gene rearrangement.