Core Immunology - Immunodeficiency (12) Flashcards
B lymphocytes
Develop potential to secrete antibodies (humoral immunity)
Killer/cytotoxic T lymphocytes
Able to kill (cellular immunity)
Helper T lymphocytes
Secrete growth factors/cytokines which control immune response - help B lymphocytes and T lymphocytes
Which cells are the target of HIV?
Helper T lymphocytes
Supressor T lymphocytes
Dampen down immune response
Binding of antibodies to antigens inactivates antigens by…
- Neutralisation (blocks viral binding sites, coats bacteria) (phagocytosis)
- Agglutination of microbes (phagocytosis)
- Precipitation of dissolved antigens (phagocytosis)
- Activation of complement system (cell lysis)
How do cytotoxic T cells work?
- Bind to infected cell
- Perforin makes holes in infected cell’s membrane
- Enzymes enters
- Infected cell is destroyed
Immunodeficiency
Clinical situations where the immune system is not effective enough to protect the body against infection
What age is immunodeficiency most common?
Can occur at any age, children and elderly are much more sensitive to infection
Primary immunodeficiency
Caused by genetic defects in individual components of the immune system
Secondary immunodeficiency
Effects of external factors
Primary immunodeficiency
- Very rare
- Diagnosed in early childhood, can present in adult life
- Recurrent infection
Secondary/acquired immunodeficiency
- Stress
- Surgery/burns
- Malnutrition
- Cancer (lymphoproliferative disease)
- Immunosuppressive effect of drugs (cancer therapy - lymphocytes/neutrophils)
- Irradiation
- AIDS
- Other infections e.g. measles, TB
Nitroblue tetrazolium test
- Incubate neutrophils with die and creates free oxidative neutrophils, if works blue > dark
- Used for chronic granulomatous disease and other diseases of phagocyte function
Chronic granulomatous disease
- Osteomyelitis (bone marrow inflammation)
- Pneumonia
- Swollen lymph nodes
- Gingivitis (inflammation of gum)
- Non-malignant granulomas
- IBD
Complement pathway test
- Incubate sheep RBC and patients serum
- Complement system should active > RBC lysis
Primary B-cell deficiencies
- Common variable immunodeficiency
- X-linked agammaglobulinaemia
- Autosomal recessive hyper IgM syndrome
- IgA deficiency
- IgG subclass deficiency
- Transient hypogammaglobuinaemia of infancy
Primary T-cell deficiencies
- Severe Combined Immunodeficiency syndromes
- Adenosine Deaminase deficiency
- Purine nucleoside phosphorylase deficiency
- MHC class II deficiency
- Wiskott-Aldrich syndrome
B cell defect
- Different degrees of loss of antibody secretion
- Recurrent bladder infection with pyogenic organisms
- Diagnosed around 1-2yrs, maternal IgG protection
Treatment for B cell defect
Antibiotics, then IV IgG for life
How serious is IgA deficiency?
Less serious then IgG, which is very serious
SCID
Defects in B and T cells
Treatment of SCID
Gene therapy or bone marrow transplantation (curative)
T cell defect
More dramatic as B cells need T cell help
Symptoms of T cell defect
Recurrent infection with opportunist infections, bacteria and viruses e.g. Fungi (candida), protozoa (pneumocystis)
