Pharmacy 211 Lecture 6: Vaccination, Hypersensitivity, and Autoimmunity

Flashcards covering vaccine types, herd immunity, the four types of hypersensitivity defined by Gell and Coombs, and the mechanisms of autoimmunity.

Herd Immunity

A state developed in a population to protect the vulnerable and minimize the chance of spread of lethal infections.

Live (attenuated) Vaccine

A vaccine that uses a whole pathogen that is dead or inactivated, causing a mild infection to stimulate immunity while the pathogen cannot multiply.

RNA and Sub-unit Vaccines

Vaccines that are immunologically less complex with fewer antigens and shorter survival of antigens, typically requiring multiple doses.

Passive Maternal Protection

Protection provided to a child in utero and at birth via $IgG$ transfer across the placenta, which does not last long after birth.

Vaccine Efficacy

The effectiveness of a vaccine at reducing the spread of disease, which is often greater than $90\%$, for example in smallpox, COVID-19, and flu.

Hypersensitivity

An excessive, over-reactive, or long-lasting immune response against foreign antigens.

Autoimmunity

A condition where the immune system fails to distinguish between self and non-self, producing immune cells or autoantibodies that target its own cells, tissues, and organs.

Gell and Coombs Classification

A $1963$ classification system for immune hypersensitivity, categorizing it into Types I, II, III, and IV.

Type I Hypersensitivity

An immune response involving $IgE$ and mast cell degranulation in response to innocuous allergens like pollen.

Allergen

A foreign antigen, such as house dust mite, peanut protein, or penicillin, that triggers an allergic hypersensitivity reaction.

Mast Cell Degranulation

The process where an allergen cross-links $IgE$ on high-affinity $FC\epsilon R$ receptors, leading to the release of mediators.

Cromoglycate

A pharmacological treatment for allergies that functions by stabilizing mast cells.

Type II Hypersensitivity

A response involving $IgG$ or $IgM$ antibodies against cell-surface antigens, leading to Antibody-dependent Cellular Cytotoxicity (ADCC) or complement activation.

Type III Hypersensitivity

A response mediated by $IgG$ and soluble immune complexes that deposit in blood vessels, often leading to vasculitis or nephritis.

Type IV Hypersensitivity

A delayed-type hypersensitivity (DTH) mediated by $T ext{ cells}$ (specifically $CD4 ext{ Th1}$ cytokines) with symptoms appearing after $24\,-\,72 ext{ hours}$.

Mantoux Test

An intradermal immune memory assessment for tuberculosis antigens, serving as an example of Type IV Hypersensitivity.

Molecular Mimicry

A process where an immune response to a bacterial peptide cross-reacts with a similar self-peptide because they look the same to $T ext{ cells}$.

Adrenalin

A sympathomimetic treatment typically administered via an EpiPen for serious hypersensitivity reactions such as anaphylaxis.