IgA Vasculitis – Henoch Scholein Purpura: Pathogenesis and Clinical Findings - Infectious Agents - 50% have preceding upper respiratory tract infections, i.e., influenza virus or Group A Strep - Drugs - I.e., antibiotics (penicillin, erythromycin), NSAlDs and biologics (tumor necrosis factor a inhibitors) - Immunogenetic and cellular predisposition - Various genetic polymorphisms alter cell-mediated immune response, IgA levels elevated in 50% of people -> Circulating galactose-deficient IgA1 (GD-IgA1). Deficiency in galactosylation of IgA1 -> Decr IgA serum clearance -> adhesion of IgA complexes, which then deposit into the endothelial lining of blood vessels -> attraction of various inflammatory cells to the area: - Formation of immune complexes - Secretion of Interleukin 8 (IL8) - cytokine that induces neutrophilic chemotaxis and macrophage phagocytosis - Neutrophils infiltrate the tissue site - Activation of complement factors (C3, C4) -> Leukocytoclastic vasculitis (histopathologic term for small vessels inflamed by neutrophilic autoimmune response) - Cutaneous small vessel vasculitis (100%) - Gastrointestinal (85%) - Colicky abdominal pain (commonly in the periumbilical region), nausea, vomiting, GI bleeding (hematemesis, melena), Intussusception - Renal (10-50%) - HTN, nephrotic/nephritic syndrome, renal insufficiency - Joints (60-85%) - Arthralgia's (common), arthritis (especially knees and ankles) #HSP #IgA #Vasculitis #HenochScholeinPurpura #Pathophysiology #Diagnosis #Signs #Symptoms
