Adaptive Immune System

How does activation of complement help fight infections?

Antibodies bind to pathogens, triggering the complement cascade, leading to inflammation, opsonization, and membrane attack complexes (MACs) that lyse pathogens

What is agglutination, and how does it aid in immunity?

Antibodies bind multiple pathogens, causing them to clump together, preventing their spread and making them easier targets for phagocytosis.

How does antibody-dependent cellular cytotoxicity (ADCC) work?

Antibodies coat a pathogen and signal NK cells to destroy it, helping eliminate virus-infected cells and some cancer cells.

What is neutralization in terms of antibody function?

Antibodies bind to toxins, viruses, or bacteria, preventing them from attaching to host cells, blocking infection and toxin effects.

How does opsonization enhance the immune response?

Antibodies coat a pathogen, making it easier for phagocytes (e.g., macrophages, neutrophils) to recognize and engulf it, leading to faster pathogen destruction.

Which type of immunity (humoral or cell-mediated) is primarily responsible for targeting extracellular pathogens?

Humoral immunity (B cells, plasma cells, and helper T cells).

Which type of immune response is more effective against intracellular pathogens, such as viruses inside host cells?

Cell-mediated immunity (cytotoxic T cells, helper T cells, macrophages, dendritic cells).

How do B cells recognize pathogens in humoral immunity?

B cell receptors (BCRs) bind to extracellular antigens directly or with the help of antigen-presenting cells.

How do cytotoxic T cells (CD8+) recognize infected cells in cell-mediated immunity?

They recognize antigens presented by MHC class I molecules on infected or abnormal cells.

What do CD4+ helper T cells do in the immune response?

They activate macrophages, enhance B cell activity, and boost the overall immune response.

What type of immune response is required for a viral infection?

Cell-mediated immunity (CD8+ T cells kill infected cells).

What type of immune response is required for a bacterial infection?

Humoral immunity (antibodies target extracellular bacteria).

What type of immune response is required for a fungal infection?

Both humoral and cell-mediated immunity.

How does the primary immune response differ from the secondary immune response in terms of speed and strength?

The primary response is slower and weaker, while the secondary response is faster and stronger due to memory B and T cells.

Which antibody is produced first in the primary immune response?

IgM, followed later by IgG.

Which antibody dominates the secondary immune response?

IgG (or IgA/IgE depending on the infection).

How do vaccines work in relation to primary and secondary immune responses?

Vaccines stimulate a primary immune response to create memory cells, allowing for a stronger and faster secondary response upon future exposure.

What is hypersensitivity, and can you give an example?

Hypersensitivity is an overreaction of the immune system to harmless substances or self-tissues. Example: Allergies (Type I hypersensitivity).

What is an autoimmune disease, and can you give an example?

An autoimmune disease occurs when the immune system mistakenly attacks the body's own cells. Example: Type 1 diabetes, rheumatoid arthritis.

What is immunodeficiency, and can you give an example?

Immunodeficiency is a weakened or absent immune response, making individuals more susceptible to infections. Example: HIV/AIDS (acquired), SCID (genetic).

How can infections contribute to the development of autoimmune diseases?

Some infections trigger autoimmunity through molecular mimicry, where pathogen antigens resemble host proteins (e.g., Streptococcus infections leading to rheumatic fever).

How can microbes cause immunodeficiency?

Chronic infections or exposure to certain pathogens (like HIV) can weaken the immune system, leading to immunodeficiency diseases.