Adaptive Immunity

Question 1

describe how dendritic cells present antigens

Answer 1

DCs digest pathogen at site of infection into short peptide fragments

DCs migrate to lymph noes where they present pathogen derived peptides on their surface via Major Histocompatibiity Complexes (MHC molecules)

Question 2

What does IgM, IgA, IgG and IgE do

Answer 2

IgG - anti-bacterial immunity, pathogen neutralization

IgA - specialised for secretion at mucousal sites

IgE - Fc part binds to mast cells causing degranulation, realeasing histamines

IgM - complement activation

Question 3

What are the functions of antibodies?

Answer 3

Formation of immune complexes (easier to phagocytose) (IgM and IgA)

Neutralisation of bacteria, toxins and viruses by blocking the binding of these to host cell and tissues (IgG and IgA)

Opsonisation (IgG)

Complement activation through binding to target cells (IgM)

ADCC, helps NK cells recognise and kill tumor of infected cell (IgG)

Mast Cell degranulation (IgE)