Primary Immunodeficiencies Flashcards
B cell defects have more infections from
Encapsulated bacteria
Invasive or chronic enterovirus
X-linked agammaglobulinemia inheritance and pathogenesis
X-linked
Mutation in BTK…Undergo heavy chain rearragnement but no light chain expression…cannot make mature B cells…reduced to absent levels of all antibodies because reduced B lymphcytes and incapable of generating plasma cells
X-linked agammabloulinemia clinical manifestation
Present at 6 mos
Recurrent and chronic sinpulmonary infection…bacterial infections from encapsulated (sepsis, mening, pneumo)…increased enteroviral infections (enteroviral meningoencephalitis)
On PE, underdeveloped lymphoid tissue and may lack tonsils and adenoids
X-linked agammaglobulinemia diagnosis
Reduced levels of AB…measure antibody titers to routine immunizations…genetic testing for BTK can confirm
HIGM syndrome inheritance
X linked of CD40L
Autosomoal recessive AID
HIGM pathogenesis
Defects in CD40 or AID…Affected macrophage activation…both CMI and HMI deficiency if CD40…only HMI if defect in activation deficiency
HIGM clinical manifestion
HUmoral defieicny common for all forms…activation defects similar to XLA…CD40L def similar to SCID…CMI deficiencies lead to intracell infections like Pneumocystis
HIGM diagnosis
Elevated IgM but reduced G, A, E…normal B and T cell numbers but reduced to absent memory B cell (CD27)…Can genetic test to confirm
IGA
Most common
Pathogenesis of IGA
Cannot really be associated with a single cause
Clinical manifestation of IGA
Recurrent sinopulmonary infections (otitis media or sinusitis…serios not common)
Allergic disorders
Autoimmune conditions (25%)
Transfusion reactions (may develop anti-IGA antibodies)
Diagnosis of IGA
Reduced levels of IgA with everything else normal
Manifestations of CMI dominated by
Deficiency in CD4 helper T response
DGS mutation and 3 things to look for
Cardiac abnormalities, hypoplastic thymus, and hypocalcemia (secondary to parathhyroid hypoplasia)…3rd and 4th pharyngeal pouch defects
DGS pathogenesis
Heterozygous deletion of T box transcription factor gene…regulates development of 3rd pharyngeal arch…degree of CMI and HMI but AB deficiency predominantes…normally have enough thymic tissue to develop T cells but defiencient in B cell activation
DGS clinical manifestation
COmplete present same as SCID…cannot form T cells and therefore no HMI or CMI
Partial can have a range depending on thymic hypoplasia…recurrent sinopulmonary infections but not normally life-threatening…early signs can resolve
DIagnosis of DGS
Measure TRECs via PCR…low TRECS suggest reduced T cells…complete DGS diagnosed with absent T and NK cells…partial will show reduced T cells
HIES pathogenesis
Defect in signal transducer and activator of transcription 3 (STAT3)…key TF in Th17 differentiation
Elevated IgE result of impaired T cell regulatory functions…cytokines increase that result in IgE, decrease that suppress IgE
HIES clinical manifestation
Diminshed Th17 function (fungal, myco, extracell) and impaired neutrohpil chemotaxis from IL-17 (skin infections)
Normally in first few week severe atopic dermatitis followed by skin infections…reccurent sinopulmonary as they get older…pneumonias are severe caused by S aureus, fungi, Pneumocystis
Can also have faical, neuro, vascular abnormalities as well
Diagnosis of HIES
Elevated IgE and eosinophilia…reduced or absent Th17 numbers