Primary immunodeficiency Flashcards
What are the hallmarks of recurrent infections encountered in immune deficient patients (SPUR)?
Serious infection
Persistent
Unususual
Recurrent
What are the stages of phagocyte production, mobilisation and recruitment that can be affected by immune deficiencies?
- mobilisation of phagocytes from bone marrow
- upregulation of ednothelial adhesion molecules. Neutrophils adhere and migrate into tissues.
- Recognition of the pathogen
- Phagocytosis of the pathogen.
- Activation of other immune system components.
Failure to produce neutrophils?
- Recticular dysgenesis (primary, severy inborn SCID)
- Following cell transplantation (secondary defect)
- Kostmann sydndrome
- Cyclic neutropaenia
When does Kostmann sydnrome present?
2 weeks after birth, with recurrent bacterial infections.
Treat with:
- stem cell transplantation
- stimulate neutrophil maturation with growth factors
What are the clinical features of leukocyte adhesion deficiencies?
- recurrent infections of deep tissues
- very high blood neutrophil counts
What receptors can be faulty in defects of phagocyte’s direct recognition of pathogens?
Toll-like receptors
Scavenger receptors
Lectin receptors
-They recognise bacterial wall structures.
Fc and complement (CRI) receptors:
-bind antigen-bound opsonins
Failure to phagocytose and kill pathogens?
-Chronic granulomatous disease (failure of oxidative killing mechanisms)
What are the features of Chronic granulomatous disease?
- recurrent Staph, Aspergillus and pseudomonas infections
- atypical mucobacteria
- fungal infections
- failure to thrive
- hepatosplenomegaly
- failure to thrive
- granulomas
Lab diagnostic test for chronic granulomatous disease?
NBT (nitroblue tetrazolium) test - can neutrophils kill pathogens by producing ROS?
What is the IL-12 : IFN-gamma network?
Defence against intracellular pathogens:
- Infected macrophages produce IL-12
- IL-12 induces Th1 cells to secrete INF-gamma
- INF-gamma loops back to stimulate oxidative killing pathways by macrophages
Where do T cells undergo maturation and proliferation?
the Thymus
How are T cells formed?
- arise form haematopoietic cells in the bone marrow
- maturation and selection in the thymus
- entry into circulation and lymph nodes
Functions of T cells?
- defend against intracellular pathogens (bacteria, viruses)
- immunoregulation (helper T cells)
Functions of CD4+ T (helper) cells?
Immunoregulation:
- activate CD8+ (cytotoxic) T cells and naive B cells
- secrete cytikines
What antigenic peptides do CD4+ / T helper cells recognise?
Those bound to MHC class II