T Cell-Mediated Immune Responses Quiz

T-Cell Mediated Immune Responses

• Two main types are T-helper (CD4+) and cytotoxic T-cells (CD8+).
• CD4+ T-cells help orchestrate immune responses, while CD8+ T-cells directly kill infected cells.

Subsets of CD4+ T-Cells

• Th1 cells: Produce cytokines to combat intracellular pathogens like viruses.
• Th2 cells: Focus on extracellular pathogens, promoting antibody production.
• Th17 cells: Involved in autoimmunity and defense against fungal infections.
• Treg cells: Regulate immune responses to maintain tolerance.

T-Cell Recognition

• T-cells recognize both intra and extracellular microbes via T-cell receptors (TCRs).

Stages of Antigen Recognition by T-Cells

• Antigen presentation by antigen-presenting cells (APCs).
• Recognition of antigen-MHC complex by TCRs.
• Co-stimulation occurs for full T-cell activation.
• Proliferation and differentiation into effector T-cells.

Responses from CD4+ T-Cell Subsets

• Th1 responses lead to cellular immunity.
• Th2 responses result in humoral immunity through B-cell activation.

Antigen Receptor Molecules

• Key regions for structural integrity include the variable and constant regions.
• Effector functions require the cytoplasmic tail and signaling domains of the receptor.

B-Lymphocyte Recognition

• B-lymphocytes recognize not just shapes of macromolecules, but also epitopes presented by proteins and peptides.

Sequence Variability in Antigen Receptors

• Concentrated in the hypervariable regions of the TCR and BCR, which determine specificity for different antigens.

T-Lymphocytes Recognition

• Recognize processed peptides displayed on APCs with major histocompatibility complex (MHC) molecules.

Features of Antigen Receptors in Adaptive Immunity

• High specificity and diversity to recognize a vast array of antigens.
• Ability to generate long-lasting memory for faster responses upon re-exposure.
• Engagement of multiple signals for effective activation and response.