Immunology Flashcards
Where are basophils and eosinophils found and what do they do?
Circulate in blood
Recruited to sites of infection
What do mast cells, basophils and eosinophils secrete?
Release chemicals such as histamine, heparin and cytokines
What do phagocytise cells do?
Ingest and kill Bactria and fungi
Clear debris from dead/dying tissues
Where are neutrophils found and what do they do?
Circulate freely in blood
Rapidly recruited into inflamed and infected tissues
What do monocytes/macrophages do?
Help limit inflammation
Tissue repair and wound healing
Involves in antigen presentation
What do dendritic cells do?
Mature and migrate to secondary lymphoid tissues and stimulate antigen presentation (adaptive immune response)
What are NK cells and what do they do?
Large granular lymphocytes
Kill tumour cells and virally infected cels
Kill anitbody bound cells/pathogens
What are B cells responsible for?
Production of antibodies
What is primary lymphoid tissue the site of?
Leukocyte development
What is secondary lymphoid tissue the site of?
Where adaptive immune responses are initiated
What is the lymphatic system?
System of vessels draining fluid from body tissues
Lymph nodes are initiated regularly along lymph vessels - remove pathogens and antigens from lymph
2 mechanisms of common cation in the immune system?
Direct contact
Indirect contact
What is the interaction between in direct contact?
Receptor:Ligand interactions
Receptor if immune cell, ligand of pathogen
What is indirect contact?
Production and secretion of cytokines
Injured tissue cells and activated immune cells can produce and secrete cytokines
What are cytokines?
Diverse collection of small proteins and peptides produced in response to infection
What is the general function of cytokines?
Coordinate immune system by ,ovulating behaviour of cells
Examples of cytokines?
Interferons
TNF
Chemotherapy
Interleukins
Functions of interferons
Antiviral functions
Function of TNF
Pro inflammatory
Function of chemokines
Control and direct cell migration
Local response to infection
Rubor (redness) Calor (heat) Tumour (swelling) Dolor (pain) Functio laesa (loss of function)
3 phases in response to invading pathogens
Recognition
Activation
Effector
What happens in regonitiom phase?
PRRs (pattern-recognition receptors)
Pathogen associated mole
IgA
2nd most abundant Ig type
Monomeric form - blood
Dimeric - great milk, saliva, tears, mucosal secretions
IgD
Extremely low levels in blood
Surface bound = BCR
IgE
Extremely low levels normally
Produced in response to parasitic infection and allergic responses
IgG
Most abundant Ig in plasma
Actively transported across placenta
4 subtypes
IgM
Surface bound monomer = BCR
1st Ig type produced in an immune response
( pentamer - present only in plasma/secretions)
How are B cells activated?
Encounter with antigen within lymph nodes
If signalled by T lymphocytes B cells rapidly proliferate
Differentiate
Function of antibodies
Identify pathogens
Recruit other immune components (complement, phagocytes, NK cells)
Neutralise toxins
Particularly important in defence against bacteria
Defect of haemopoetic stem cells
Reticular dysgenesis
Defects of lymphoid precursors
Severe combined immunodeficiency (SCID)
Failure of production of lymphocytes
Clinical features of SCID
Unwell by 3 months old Persistent diarrhoea Failure to thrive Continuous infections Unusual skin disease Family history of early infant death
How long does maternal IgG protect baby for?
3 months
Most common form of SCID
X-linked SCID
Mutation of IL-2 receptor (inability to respond to cytokines)!
Produces immature B cells
Treatment for SCID
Prophylactic
- avoid infections (antibiotics, antifungals, no vaccine)
- aggressive treatment of existing infections
- antibody replacement (IV immunoglobulin)
Definitive
- stem cell transplant (sibling)
- gene therapy
What is DiGeorge syndrome?
Chromosomal deletion Congenital heart defects Cleft palate Hypoparathyroidism Psychiatric disorders
Clinical presentation of DiGeorge syndrome
Funny looking kid
- low set folded ears
- high forehead
- cleft palate, small mouth & jaw
- hypocalcaemia
- oesophageal atresia
- T cell lymphophopenia
- congenital heart disease
Investigations for DiGeorge syndrome
Absent or decreased T cells
Normal or increased B cells
Normal NK cell numbers
Management of DiGeorge syndrome
Prophylactic antibiotics
Aggressive treatment of infection
Immunoglobulin replacement
T cell function improves with age
Disorders of T cell effector function
Cytokines production
Cytotoxicity
T-B cell communication
Infections caused by issues with IL12 gIFN network
TB
Atypical mycobacteria
BCG infection after immunisation
Deep fungal infections (e.g. Aspergillus)
Where are mast cells found and what do they do?
Reside in tissues and protect mucosal surfaces
Clinical features of common variable immune deficiency
Recurrent bacterial infections
Autoimmune disease
Granulomatous disease
What does CRP show?.
Degree if inflammation
Functions of complement
Opsonisation Inflammation Chemotaxis Membrane attack complex Clearance of immune complexes
What is an antigen?
A substance which can cause an adaptive immune response by activating B cells and T cells
Where do adaptive immune responses occur?
Secondary lymphoid tissue
