Allergy/Immunology Flashcards
What is the most common form of SCID?
X-linked, about 50% are of this variety
What is the mutation in X linked SCID
mutation in the cytokine receptor subunit gamma chain which is a component of several cytokine receptors including those or interleukins.
T cells do not develop.
Maternal T cells engraft but they do not work well,
B cells are present but do not work well
What is the resulting flow cytometry of X linked SCID
B+ T cell - and NK cell -
What medical intervention should not be given to a child with SCID?
Live virus vaccines
What kind of blood does a child with SCID need and why?
Irradiated
because non-irradiated blood has T lymphocytes which can cause graft vs hose disease
What clinical and laboratory findings do children with SCID have?
lymphopenia
absence of a thymus shadow on chest XR
present with overwhelming sepsis, eczematous like skin lesions, chronic lung infections, diarrhea and failure to thrive. PCP pneumonia, candidiasis, CMV pneumonia
What purine salvage pathways disorders manifest as SCID?
adenosine deaminase deficiency
purine nucleoside deficiency
How does ADA cause immunodeficiency?
accumulation of deoxyadenosine and deoxyadenosine trisphospate accumulate in lymphocytes which kills the lymphocytes. so no b cells, t cells or NK cells.
What skeletal abnormalities are seen with adenosine deaminase deficiency
cupping and flaring of the costochondral junction and pelvic dysplasia
what autoimmune disease is common in those with purine nucleoside phosphorylase deficiency
Rare, less severe than ADA
autoimmune hemolytic anemia and thrombocytopenia
What is RAG deficiency?
autosomal recessive
most severe form of SCID and accounts for 25-30%
mutation/deletion in RAG 1 and 2 genes that makes the cell unable to rearrange the genes for immunoglobulin and for T cell antigen receptors.
B and T cells do not work. NK cells are ok
What is reticular dysgenesis
Form of SCID where myeloid and lymphoid cell lines do not develop.
What is Omenn Syndrome
variant of RAG deficiency, with partial as oppose to complete deletion
present with erythroderma, diarrhea, hepatosplenomegaly and failure to thrive.
hypogammaglobulinemia, elevated IgE and marked eosinophilia.
What is bare lymphocyte syndrome
Failure to express MCH class 2 molecules have guarded prognosis even after bone marrow transplant
What is Waiskott-Aldrich Syndrome?
x-linked EXIT: eczema x linked immune deficiency thrombocytopenia
What symptoms and signs are suggestive of Waiskott-Aldrich Syndrome?
abnormal bleeding bloody diarrhea eosinophilia and increases IgE recurrent sino pulmonary infections, chronic otitis media, severe viral infections small platelets are diagnostic
What immunoglobulins are made or not made in Waiskott-Aldrich Syndrome and what is the treatment?
Makes IgA and IgE and IgG
Does not make IgM
since the respond poorly to vaccines, IVIG is recommended
What are the main characteristics of Ataxia-Telangiectasia?
cerebellar ataxia
oculocutaneous telangiectasia
immunodeficiency
high incidence of cancer with increased sensitivity to radiation
How does ataxia-telangiectasia present? How is it diagnosed?
Around the age of 5 starts to have ataxia, telangiectasias also start to appear at age 5, but sometimes later
sinopulmonary disease with bronchiectasis
Diagnosis is ataxia plus telangiectasias plus positive alpha fetoprotein
immune problems are usually less than the ataxia
What are children with ataxia-telangiectasia most at risk for?
lymphocytic leukemias or lymphoma
What are the signs of Bloom syndrome?
deficiency in DNA ligase 1
small stature, telangiectasia, CNA abnormalities and immunodeficiency
at risk for leukemia
What are the signs of Nijmegen Breakage syndrome
“bird like” face and microcephaly with normal IQ
cellular and humoral deficiency
high incidence of lymphoid cancers
What chromosomal deletion causes DiGeorge Syndrome?
Catch 22
22q11
What are the clinical signs of DiGeorge?
cardiac abnormalities ( tetralogy, transposition of great vessels, VSD, double outlet RV)
hypoparathyoirism
thymus abnormalities
micrognathia, hypertelorism, low set ears, small philthrum
What is the immune deficiency like in DiGeorge?
immunodeficiency with severity depending on extent of syndrome, can be SCID like, some will get better with time
IVIG used if antibody production is poor
What is Nezelof Syndrome
autosomal recessive form of thymic hypoplasia
leads to varying degrees of T-cell dysfunction
How does X-linked (Burton’s) agammaglobulinemia present?
Recurrent bacterial infections particularly pneumonia, ear infections, sinusitis.
Often testing is prompted after boy over 1 year of age has been treated over and over again with antibiotics.
What is X-linked agammaglobulinemia?
mutation in gene BTX burton’s tyrosine kinase at Xq22
this is necessary for b cell development so there are only pre-b cells in circulation, no mature b cells
How is x-linked agammaglobulinemia diagnosed and treated?
severe deficiency of all immunoglobulins
need at least monthly IVIG
small tonsils and lymph nodes
What are the symptoms and lab values of Common Variable Immunodeficiency
recurrent sinopulmonary infections with encapsulated bacteria
deficiency in at least two classes of immunoglobulins (IgG, IgM or IgA) and poor immunoglobulin function as demonstrated by low vaccine titers to Dtap and pneumococcus
IgG < 300
IgA and IgM < 50
What other findings are associated with CVID?
sarcoid like disease with noncaseating gramulomas of spleen, liver, lungs, and skin
may have hepatosplenomegaly
autoimmune conditions: (ITP, pernicious anemia, hemolytic anemia, malabsorption, pancytopenia)
sprue like illness: diarrhea, malabsorption, protein losing enteropathy, steatorrhea
increase incidence of lymphoma
giardia
chronic enteroviral meningitis
How is CVID treated?
IVIG and specific therapy for infectious complications
What is the deficiency in Hyper-IgM syndrome?
deficiency in IgG and IgA with normal or high IgM
What is the genetics and cause of Hyper-IgM syndrome
can be either x-linked or AR X linked is due to deficiencies in coding CD40 ligand on T cells so, b cells can not class switch to more specific antibodies
How does hyper IgM syndrome present?
recurrent sino pulmonary infections particularly with encapsulated organisms, giardiasis and meningitis
X-linked also susceptible to PCP
How is Hyper-IgM syndrome treated?
IVIG and prophylaxis for those at risk for PCP
bone marrow transplant is considered for those with x-linked variety