Immunopathology II Flashcards
what cell regulates both the humoral and cellular components of the immune system?
mature T4 cell
what is the cause of X linked agammaglobinemia?
mutation in tyrosine kinase gene responsible for pro/pre B cell signal transduction and continued B cell maturation
which antibody crosses the placenta?
IgG
patients with agammaglobinemia are susceptible to what types of infections?
enteric viruses and protozoa (no IgA)
what is the main feature of common variable immunodeficiency?
hypogammaglobinemia, usually all Ab classes but sometimes isolated to IgG
what is the mechanism of common variable immunodeficiency?
- intrinsic B cell defect 2. abnormal T cell signaling to B cells (increased suppression or decreased helper activity) 3. inability of B cells to mature into plasma cells
what is the mechanism for selective IgA deficiency?
IgA and B cells fail to mature
what are the symptoms of selective IgA deficiency?
- recurrent GI, respiratory, GU infections secondary to weakened mucosal defenses 2. increased risk for AI disorders (RA, SLE) 3. 40% have anti-IgA antibody
what is the cause of hyper IgM syndrome?
failure of T cells to: 1. induce B cell isotype switching from IgM to IgG/A/E, and 2. activate macrophages to remove intracelullar microbes
IgM producing B cells normally activate transcription genes that encode for other Ig isotypes via what signaling process?
signaling between CD40 on B cells and CD40L on Th cells
what are the levels of IgM in hyper IgM syndrome?
normal or elevated
hyper IgM syndrome has what type of inheritance?
- X linked 70% 2. autosomal recessive for mutation of CD40 gene or activation induced deaminase enzyme required for switching
what are the clinical symptoms of hyper IgM syndrome?
- recurrent pyogenic infections (no opsonizing IgG) 2. intracellular infections (P. jiroveci, no phagocytosis) 3. AI lysis (anti-RBC IgM reaction) 4. GIT lymphoid hyperplastic accumulations of IgM+ B cells
what are the features of DiGeorge syndrome?
T cell defect, hypocalcemia, cardiac abnormalities, cleft palate
what are the dysmorphologies of DiGeorge syndrome?
- facial - low set ears, midline clefts, small mandible 2. cardiac - VSD, right subclavian artery derived from pulmonary artery