Primary Immunodeficiency Flashcards
When a patient has an ID (immunodeficiency), they are more likely to develop…
Lymphomas or Autoimmune diseases
B Cell Defect
When will it first manifest?
3-6 months after birth (before then, the child is protected by Mom’s antibodies)
B Cell Defect
Clinical Manifestations
Recurrent sino-pulmonary infections and septicemias caused by infection with extracellular pyogenic bacteria
B Cell Defect
What is the pt more likely to get infected with?
Encapsulated bacteria
Strep, Staph, Haemophilus
Also susceptible to systemic and atypical CNS disease with enteroviruses normally found in GI tract
T Cell Defect
When will it first manifest?
At birth
T Cell Defect
Clinical Manifestations and Likely infections
Infections that require T cell/macrophage interaction
Listeria, Mtb, Toxoplasmosis, fungi, protozoa Most viruses (from CD8 lack)
A B and T cell defect is known as…
Severe Combined Immunodeficiency (SCID)
When would a baby with SCID first get sick?
At birth
What is the general difference in the kinds of recurrent infections found in B cell defects vs. T cell defects?
B cell defects
Mostly Bacterial
T Cell defects
May include viral, fungal, opportunistic infections too
In general, how would you test whether a patient has a B cell defect?
Measure serum immunoglobulin
Do a serum protein electrophoresis
In general, how would you test whether a patient has a T cell defect?
Do a blood count with CBC –> do they have lymphocytes?
Could also measure whether they mount a positive skin test to common antigens (like Candida or Histoplasmosis)
What surgical procedure must be done with extreme care in people with immunodeficiencies? Why?
Lymph node biopsy
Very easy to get an infection with a sloppy surgeon
What is the only truly pure B cell defect?
X linked agammaglobulinemia
X linked agammaglobulinemia
Where is the mutation?
BLK Receptor, a signaling tyrosine receptor needed for growth and development of B cells
X linked agammaglobulinemia
What is the basic pathological problem?
The patient has no normal B cells anywhere, so they have almost no antibody present in circulation!
X linked agammaglobulinemia
Treatment
IVIG
Hyper IgM Syndrome
Where is the mutation?
CD40L, a receptor on T cells
Hyper IgM Syndrome
What is the pathogenesis?
Mutation of CD40L prevents isotype switch from occurring
Inability of T cells to be activated and provide cytokines for isotype switch
No isotype switch –> log IgG, low IgA, high IgM
Hyper IgM Syndrome
Treatment
Sten Cell Transplant
Selective IgA Deficiency
What is the pathogenesis?
IgG and IgM levels are normal, but IgA levels are decreased/absent.
No increased infections because IgG and IgM simply substitute for IgA
Selective IgA Deficiency
What is the major concern with these patients?
These patients may develop IgG anti-IgA antibodies.
If they need a blood transfusion, there will likely be residual IgA on the donor RBCs and the patient will mount an immune response. Could cause anaphylaxis and death in IgA deficient patients
EBV X linked agammaglobulinemia
What is the mutation and how does it become activated?
Mutation in signaling receptor of CD8 cells, which becomes activated by EBV infection of B cells
EBV X linked agammaglobulinemia
Pathogenesis
The mutation in the CD8 receptor renders the CD8 cell unstoppably active, causing the T cells to kill any lymphocyte they see.
Causes global immune dysfunction and death
Common Variable Immunodeficiency (CVID)
What is the fundamental defect?
Inability of a B cell to differentiate to a plasma cell
