Immunology - Diseases & Specific Findings Flashcards
SS-A (anti-Ro) / SS-B (anti-La)
Sjogren’s Syndrome
Dermatomyositis - Clinical and Histological Findings
Malar / heliotrope rash
‘Shawl sign’
Gottron’s papules / ‘mechanic hands’
Histology shows perimysial CD4 inflammation
Polymyositis - Histology
Histology shows endomysial CD8 inflammation
Nitroblue tetrazolium (NBT) test
Negative in chronic granulomatous disease
Looks for production of superoxide anion which reduces the test indicator to produce blue color
Catalase positive bacteria
Pseudomonas Listeria Aspergillus Candida E. Coli S. aureus Serratia
Pathogens associated with Guillian-Barre Syndrome
Campylobacter jejuni
CMV
Pathogens associated with Hyper-IgM syndrome
Pyogenic infections, especially:
Pneumocystis
Cryptosporidium
CMV
Pemphigus Vulgaris - Antibody, IF, special sign
anti-demoglein
IF shows antibodies surrounding epithelial cells in a ‘reticular’ arrangement
Positive Nikolsky sign = separation of the epidermis with mechanical stroking
Direct Coomb’s Test
Used to detect the presence of anti-RBC antibodies in a patient’s serum sample
RBCs from patient serum are incubated with anti-IgG antibodies; if RBCs agglutinate then RBCs were bound by antibody
Indirect Coomb’s Test
Used to detect antibodies in patient serum, i.e. prior to blood transfusion
Patient’s serum is mixed with donor RBCs; if antibodies are present in the serum which bind donor RBCs then addition of anti-IgG to the solution causes agglutination
Seronegative arthropathies - HLA association
HLA B27
Psoriatic Arthritis
Ankylosing Spondylitis
IBD-related arthritis
Reactive arthritis
Celiac Disease - HLA Association
DQ2
DQ8
Diabetes Mellitus Type 1 - HLA Associations
DR3
DR4
Which cytokines are secreted by Th2s?
IL-4 - Enhances class switching to IgE and IgG
IL-5 - Enhances class switching to IgA; stimulates growth and differentiation of eosinophils
IL-10 - Inhibits differentiation of T cell progenitors into Th1
Which cytokines are secreted by Th1s?
IL-2 - Provides 2nd signal for activation of CTLs
IFNy - Stimulates macrophages
Rheumatoid Arthritis - HLA Association
HLA DR4
SLE - HLA Association
HLA DR2
HLA DR3
Edrophonium challenge test
Edrophonium is a short-acting AChEI used to diagnose Myasthenia Gravis; symptoms of myasthenia gravis improve with administration of edrophonium
Anti-phospholipid antibody
AKA ‘Lupus anticoagulant’ - acquired anti-phospholipid antibody; bind to platelet phospholipids, making them accessible to clotting factors and leading to recurrent venous and arterial thrombosis
Inhibits the function of exogenous platelet phospholipids used in PTT assay causing false elevation (looks like a bleeding disorder)
Requires lifelong anti-coagulation therapy
Reacts with cardiolipin antigen used in syphylis serology, causing false positives for syphilis
What antibodies are most specific for SLE?
anti-Smith
anti-double stranded DNA
Which auto-antibody causes false positives in syphylis testing?
Anti-phospholipid antibody (Lupus)
What antibodies are seen in Churg-Strauss Syndrome?
anti-MPO
p-ANCA
ANCA-associated vasculitidies
Churg-Strauss Syndrome
Wegener’s Granuloamotosis
Microscopic polyangiitis
Negatively Birefringent crystals
Crystals are yellow under parallel light, blue under perpendicular light
Characteristic of monosodium urate (MSU) crystals seen in Gout
Gout
Inflammatory monoarthritis caused by precipitation of monosodium urate (MSU) crystals in joints, secondary to hyperuricemia (90% due to under-excretion of urate)
Presents as asymmetric appearance of painful, red, swollen joint, classically the MTP of the big toe (Pedagra); 20% eventually develop Gouty Nephropathy due to MSU deposition in adrenal medulla, uric acid renal stones causing renal failure
Findings: Needle-shaped, negatively birefringent crystals in joint fluid
Acute treatment = NSAIDs / Colchicine, Glucocorticoids
Chronic treatment = Xanthine Oxidase inhibitors (Allopurinol)
Drug-Induced Lupus
Seen in men and women equally, associated with anti-nuclear antibody (ANA) and anti-histone; not associated with anti-DNA antibodies (anti-dsDNA, anti-Smith)
Caused by: Hydralazine Isoniazid Procainamide Phenytoin
Lambert-Eaton myasthenic syndrome
Autoimmune production of antibodies directed against the pre-synaptic voltage-gated Ca2+ channel at the NMJ; often occurs as paraneoplastic syndrome of small cell lung cancer
Presents as proximal muscle weakness, diplopia, decreased DTRs; muscle weakness improves with exercise due to accumulation of pre-synaptic Ca2+
Kaposi Sarcoma
Neoplasm of vascular endothelial cells caused by HHV-8; seen in the setting of immunosuppression (AIDS, transplant)
Presents as dark, flat or papular lesions on the skin; may also affect GI tract and lungs
Treated with alpha interferon
Chronic mucocutaneous candidiasis
T cell dysfunction resulting in deficient or absent T-cell proliferation response to Candida antigens
Presents as recurrent oral / esophageal thrush, vulvovaginitis
Treated with fluconazole / capsofungin (for oral/esophageal) and topical -azole (for vulvovaginitis)
X-linked (Bruton’s) hypogammaglobulinemia
X-linked defect in BTK tyrosine kinase causing failure of B cell maturation and immunoglobulin production
Presents with recurrent pyogenic bacterial infections after 6 months (once maternal IgG is depleted)
Labs: Normal CD19+ B cell count, decreased Ig of all classes, absent/scanty lymph nodes and tonsils
Selective IgA deficiency
Most common primary immunodeficiency
Majority asymptomatic but can see airway or GI infections, as well as anaphylaxis to IgA-containing blood products
Labs: Low IgA with normal IgG, IgM
Severe Combined Immunodeficiency (SCID)
Autosomal recessive defect in adenosine deaminase enzyme; accumulation of ATP and dATP imbalances nucleotide pool via feedback inhibition of ribonucleotide reducetase, preventing DNA synthesis and decreasing lymphocyte count
Presents with failure to thrive, chronic diarrhea, thrush; repeated bacterial, viral, fungal, and parasitic infections
Findings: Absent thymic shadow on CXR, absent germinal centers on lymph node biopsy, low IgG/IgM, low / absent T cells
