Immunology Flashcards
Cells of the immune system: granulocytes
BEN
- Basophils- stain blue
- Eosinophils- stain pink
- Neutrophils
Cells of the immune system= antigen presenting cells
- Dendritic cells
- Monocytes- only found in the blood
- Macrophages- stays in the tissue, does not circulate in the blood
- B cells
Cells of the immune system= lymphocytes
25% of total WCC in peripheral blood
CD34+ HSCT in bone marrow
IL2 = T, B + NK growth factors
IL7 + IL15 = T + NK development
- T cells (adaptive immune system)
- B cells (adaptive immune system)
- NK cells (innate immune system)
Cells of the immune system = phagocytes
- Neutrophils, Monocytes, Macrophages
- Receptors
- Fc= Ig
- C3b= complement
Function of dendritic cells
- ONLY antigen presenting cell that activates NAIVE T cells + initiates an immune response
- Critically important in vaccination
- Short lifespan = 3 days
- Single dendritic cell can present an antigen to several T cells
Immunodeficiency conditions resulting in: recurrent sinopulmoonary infection
- Antibody production defects
- CVID
- X linked agammaglobulinaemia (XLA)
- Transient hypogammaglobulinaemia of infancy
- Complement protein deficiencies
Immunodeficiency conditions resulting in: broad infectious susceptibility + FTT
- SCID
- Wiskott Alrich
- DiGeorge
- Ataxia telangiectasia
What is the cause?
XLA: x-linked agammaglobulinaemia
Absent B cells + hypogammaglobulinaemia
CD3
T cell marker
CD19 + CD20
B cell marker
CD56
NK cell marker
CD4
Helper T cell marker
CD8
Cytotoxic T cell marker
Disorders of humoral immunity (B cell differentiation + antibody production)
- Onset
- Pattern of infection
- Other features
X linked (Bruton’s) agammaglobulinaemia
- KEY features
- Gene + protein implicated
- Clinical manifestations
- Investigations
- Management
Hypogammaglobulinaemia, NO circulating B cells, absent tonsils/lymph nodes
- Gene + protein implicated
- Xq22- XLA gene
- Bruton tyrosine kinase deficiency = pre B cell arrest
- Males 1:100 000- 1:200 000
- Clinical manifestations
- Well until ~ 6 months of age (maternal IgG antibodies protective until then)
- Lymphoid hypoplasia
- Recurrent infections with extracellular organisms (strep pneumonia, Haemophilus)
- Viral infections usually handled except hepatitis + enterovirus
- Paralysis with poliovirus
- Chronic fungal infections
- Types of infections: sinusitis, OM, pneumonia, sepsis, meningitis
- Associated with rheumatoid arthritis, sarcoid
- Investigations
- Neutropenia at HEIGHT of infection
- Peripheral blood B lymphocytes <1%
- High T cell percentage, normal T cell subset ratios
- Normal T cell function + thymus
- LOW or absent immunoglobulins
- Antibodies to vaccines absent
- Intestinal biopsy= absence of plasma cells
- Prenatal testing can be performed
- Management
- Lifelong IVIG (does NOT correct IgA deficieincy or prevent enterovirus)
- Antibiotics
D) Specific antibody responses to vaccine antigens should be assessed
Criteria for common variable immunodeficiency (CVID)
T cell dependent + independent vaccines
-
T cell dependent: isotype switched, high affinity, long lived plasma cells (IgA, IgG, IgE)
- Protein vaccinations (Diptheria, tetanus, HiB, PCV)
-
T cell independent: mainly IgM, short lived plasma cells
- Polysaccharide vaccinations (Pneumovax 23)
What is the diagnosis?
Severe combined immunodeficiency
- PJP + FTT + thrush
- Anaemia + lymphopenia
- Hypogammaglobulinaemia
- Low CD3 (T cell marker) + CD56 (NK cell marker)
- PHA (T cell mitogen response) = low
X-linked Hyper IgM = T cell defect
Chronic granulomatous disease
What is recognised by the innate immune system?
PAMPS + DAMPS
CD28
Co stimulatory molecule on T cells which binds to B7 on antigen presenting cells and causes proliferation + differentiation. If B7 on the APC not present then it will not cause activation of the T cell.
CTLA4
- Inhibitor of T cell activation. Binds to B7 on APC and inactivates it.
- HIGHER affinity to B7 than CD28
