Adaptive Immunity Overview Quiz

Adaptive Immunity Overview

• Adaptive immunity is a slower, specific immune response to pathogens.
• It involves lymphocytes, specifically T cells and B cells.

T Cell Activation

• T cell receptors bind to antigens presented by MHC molecules.
• This binding, along with co-stimulation, activates the T cell.
• Signal transduction inside the T cell causes activation.
• Two main types of T cells are Helper T cells (CD4+) and Cytotoxic T cells (CD8+).

MHC Class I and II

• MHC Class I molecules are found on all nucleated cells and present endogenous antigens to cytotoxic T cells.
• MHC Class II molecules are found on antigen-presenting cells (APCs) like dendritic cells, macrophages, and B cells and present exogenous antigens to helper T cells.

T Cell Types and Functions

• Helper T cells (CD4+) release cytokines to activate other immune cells like cytotoxic T cells and B cells.
• Cytotoxic T cells (CD8+) kill infected or cancerous cells through various mechanisms including perforin and granzymes or by activating the "death receptor" Fas.

B Cell Activation

• B cells can be activated by antigen binding to B cell receptors (BCRs).
• Helper T cell activation plays a crucial role in B cell activation, especially for antibody production and memory.

Immune Responses to Pathogens

• Antibodies, from activated B cells, act as opsonins, making pathogens easier for macrophages to engulf.
• Macrophages process and present antigens, activating other cells in the immune response.

Immune Responses to Non-Pathogens; Allergy

• Allergic reactions involve exaggerated immune responses to harmless substances (allergens)
• Two main types are immediate hypersensitivity (IgE response) and delayed hypersensitivity.
• Immediate hypersensitivity is a fast, often severe, response involving mast cell activation and release of inflammatory mediators.

Blood Types and Transfusions

• Blood type is determined by antigens on red blood cells (RBCs).
• ABO blood group has A, B, AB, and O types.
• Rh factor (positive or negative) is another important blood type characteristic.
• Cross-reactions during blood transfusions occur if donor antigens trigger recipient antibodies, causing agglutination and hemolysis.

Rh Factor and Pregnancy

• Rh-negative mothers can develop anti-D antibodies if exposed to Rh-positive fetal blood.
• This can lead to hemolytic disease of the newborn if the mother has subsequent pregnancies with Rh-positive fetuses.
• Doctors can prevent this by administering anti-D antibodies to Rh-negative mothers.

Preventing Hemolytic Disease of the Newborn

• Injecting anti-D antibodies into Rh-negative mothers during and after their pregnancy can prevent Rh-positive fetal blood from triggering an immune response.

Summary

• T cells activate through binding to MHC-bound antigens.
• Immediate hypersensitivity is an exaggerated immune response.
• Knowing blood types is crucial to avoid transfusion reactions.
• Rh incompatibility during pregnancy can cause hemolytic disease of the newborn.
• Doctors administer anti-D antibodies to Rh-negative mothers to prevent this.