Immunological Memory and Vaccination

does not include diagrams as of now → study those separately

1. what are the thre major subsets of memory T cells?

1. Central memory T cells

2. effector memory T cells

3. Tissue - Resident memory T calls

what do central memory T cells do?

Express chemokine receptor CCR7 and move to the secondary lymphoid tissues similar to naive T Cells. Upon stimulation, Tcm differentiate into Tem cells

What do effector memory cells do

mostly recirculate between the blood and non-lymphoid tissues. They can rapidly enter in flammed tissue to perform effector T cell functions

what do tissue-resident memory T cells do?

Take up long-term residence in various epithelial sites

They are close by and available in case an infection happens again - they can react quickly

what are the two ways of achieving immunization?

1. Passive Immunization

2. Active immunization

what is passive immunization?

the administration of preformed antibodies in order to give temporary protection against infection

lecture examples of passive immunization:

• Maternal antibodies in a newborn

• Pooled lgG from immunized humans can be used to provide emergency protection

what is the goal of active immunization?

to generate protective immunity and immunological memory so that a subsequent exposure to the pathogen will stimulate a vigorous immune response leading to the elimination of the pathogen

lecture examples of active immunization:

• Natural infection

• Vaccination

Passive immunization risk: Repeated administration of gamma-globulin from foreign species

can cause systemic anaphylaxis (Type I hypersensitivity) if IgE is made against the foreign protein

Passive Immunization risk: serum sickness

(Type Ill hypersensitivity). caused by immune complex deposition if there is an IgM or IgG response to the foreign protein

Passive immunization risk: Human gamma-globulin

can trigger an anti-allotypic antibody response, resulting in Type I or Type Ill hypersensitivity

How do vaccines stimulate adaptive immune responses to a pathogen without developing disease?

• induction of B cells/humoral immune response to neutralization and / or elimination of pathogen

• induction of T Cell /cell mediated immune response to kill infected cells and prevent the spread of infection

T and B cell role in vaccination (generally)

vaccination induces memory T and B cells for long term protection upon re-exposure to the same pathogen

What is herd immunity?

Indirect protection from infectious disease due to a large percent of the population becoming immune to infection.

It is essential to protect the members of the population that cannot be vaccinated like newborn babies, pregnant or breastfeeding women, Immunocompromised individuals

what are the two vaccine component

antigen and adjuvant

what is an antigen in a vaccine? 

Any substance capable of inducing a specific immune response, and is capable of reacting with the product of that response

eg. killed or attenuated whole pathogen, or protein or recombinant protein derived from the pathogen

what is an adjuvant in a vaccine?

a substance that enhances the immunologenicity of an antigen by either stimulating innate immune recognition of antigen, or enhancing stability and interactions of antigens with the immune system.

Examples of adjuvants in vaccines

• Molecules that mimic PAMPs and stimulate the innate immune systems PRRs