Autoimmine testing Flashcards
Def of Autoimmunity
- The process where the host immune system ceases to recognize one or more of the body’s normal constituents as self, creates autoantibodies that starts to attack its own (Cells - Tissues - Organs) causing inflammation & damage.
Examples of Autoimmunity
- Systemic Lupus Erythematosus (SLE).
- Rheumatoid Arthritis.
Causes of Autoimmunity
Mostly Unknown
Def of Autoantibodies
- Proteins created by the immune system when it fails to distinguish between self-antigens & non-self-antigens (foreign antigens) e.g. bacterial or viral.
what are Autoantibodies directed against?
These autoantibodies may be directed against a variety of substrates including:
- Intra-cellular antigens.
- Cell surface antigens.
- Extracellular antigens.
SLE
Immunological testing for SLE
- Antinuclear antibodies (ANA)
- SLE specific antibodies
- Complement proteins
- Anti-platelet antibodies & Anti-erythrocyte antibodies
- Anti-histone antibodies
- RF (Rheumatoid factors)
Antinuclear antibodies (ANA) in Testing for SLE
- Highly sensitive (Seen in large proportion of patients).
- But not specific (Seen in other autoimmune diseases).
SLE specific antibodies in Testing for SLE
Complement proteins in Testing for SLE
- Decrease Serum complement (C3-C4)
- Due to its consumption.
Anti-platelet antibodies & Anti-erythrocyte antibodies in Testing for SLE
- Present in about 70% of patients.
- Responsible for hemolytic anemia & thrombocytopenia.
Anti-histone antibodies in Testing for SLE
- Present in drug induces lupus.
RF (Rheumatoid factors) in Testing for SLE
+ve in 30% of patients.
Def of Rheumatoid Arthritis
- Chronic systemic inflammatory auto immune disease that affect the joints.
Immunological testing for Rheumatoid Arthritis
- Specific tests
- Others
Specific tests for Rheumatoid Arthritis
- Rheumatoid factors (RF): Positive in 75% of patients.
- Anti-CCP autoantibodies (Anti-Cyclic Citrulinated Peptide)
Charaters of Anti-CCP autoantibodies (Anti-Cyclic Citrulinated Peptide) in testing for RA
- Highly specific for RA (96%).
- They appear before the onset of RA symptoms.
Other tests for RA
- Serum complement: Decrease in presence of vasculitis.
- Antinuclear antibodies (ANA): May be positive.
- Hypergammaglobulinemia & Cryoglobulinemia.
Def of Immunodeficiency disorders
- Deficiency of one or more of the 4 major components of the immune system (B lymphocytes - T lymphocytes - phagocytic cells - complement system).
- Which protect the individual against different viral, bacterial, fungal and protozoal infections.
what are Primary Immunodeficiency disorders?
- B cell Immunodeficiency Disorders.
- T cell Immunodeficiency Disorders.
Classification of Immunodeficiency disorders
- Primary immunodeficiency diseases (Presented from birth)
- Secondary immunodeficiency diseases (Acquired due to infection as AIDS).
Examples of B-Cell Immunodeficiency disorders
Examples of T-Cell Immunodeficiency disorders
DIGEORGE’S SYNDROME
(CONGENITAL THYMIC APLASIA)
Clinical Features of T-Cell Immunodeficiency disorders
Laboratory assessment of immune competence
- Complement assay
- Evaluation of Humoral (B cells) mediated immunity
- Evaluation of Cellular (T cells) mediated immunity
- Assessment of phagocytic function
Methods of Complement assay
- Immunoassay “Assay of C3 & C4 levels”
- Functional “Hemolytic assay CH50”
Methods of Immunoassay “Assay of C3 & C4 levels”
- Electro immunodiffusion
- Rate nephelometry
- ELISA
- Single radial diffusion
Methods for Evaluation of Humoral (B cells) mediated immunity
- Protein electrophoresis
- Quantitative immunoglobulins level
- IgG subclasses level
- Total B cell count
- Specific antibody response after immunization in vivo
- Stimulation of B cells in vitro
Methods of Quantitative assessment of immunoglobulins level
- Radial immunodiffusion
- Nephelometry
- ELISA
Methods of assessment of IgG subclasses level
ELISA
Methods of assessment of Total B cell count
- Using Flow cytometry
- Normally 10 - 20% of total circulating lymphocytes
Specific antibody response after
immunization in vivo
Principle: Immunization with tetanus or pneumococcal polysaccharide Antigens
Stimulation of B cells in vitro
- By Mitogen or Antigen, and assessment of immunoglobulin release
Evaluation of Cellular (T cells)
mediated immunity
- Total Lymphocytes count
- Monoclonal antibodies to T cell subsets
- Total T cell count
- Delayed cutaneous hypersensitivity skin test in vivo
- Lymphocyte response in vitro
MOAs = Method of assessment
MOAs of Total Lymphocytes count
Normally > 1200/ul “At any age”
MOAs of Monoclonal antibodies to T cell subsets
Using Flow cytometry
MOAs of Total T cell count
- Using Flow cytometry
- Normally >60% of total circulating lymphocytes
MOAs of Delayed cutaneous hypersensitivity skin test in vivo
- Using PPD
- Used to evaluate specific cellular immunity to antigen
MOAs of Lymphocyte response in vitro
- By Mitogen or Antigen
Assessment of phagocytic function
- Nitro-blue tetrazolium test
- Chemiluminescence
- Chemotaxis
- Assessment of superoxide production
- Enzyme tests
- Genetic analysis
what is Nitro-blue tetrazolium test used in?
Used lo diagnosis of CGD
Chemiluminescence
Albnormal in…
* CGD
* Myeloperoxidase deficiency
MOAs of Chemotaxis
- Principle: Measure ability of neutrophils to move in a directed, migratory pattern toward chemotactic substance
when is Chemotaxis abnormal?
- Abnormal in various disorders “Not specific”
Superoxide production in CGD
- Absenl in CGD
- Defective in other syndromes
Genetic analysis
Available for
* CGD
* LAD
* Chediak Higashi syndrome
Indication of Enzyme tests
- e.g., G6PD - Myeloperoxidase
