This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vasculitis, Subject name: Medicine
[{'content': 'In Henoch schonlen purpura Ig and complement involved: \nSelect and explain. \nA. IgG, C 3, B. IgA, C 3, C. IgA, Cl, D. IgG, Cl', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. (b) IgA, C 3Ref: Harrison 19th ed. / 2190* Henoch Schonlein purpura is a small-vessel vasculitis in which complexes of immunoglobulin A (IgA) and C3 are deposited on arterioles, capillaries, and venules.* As with IgA nephropathy, serum levels of IgA are high in HSP .* IgA nephropathy has a predilection for young adults while HSP is more predominant among children. Further, IgA nephropathy typically only affects the kidneys while HSP is a systemic disease.* HSP involves the skin and connective tissues, scrotum, joints, gastrointestinal tract and kidneys.* Investigation: IgA levels high, platelet count normal and skin biopsy (IOC).* Treatment: steroids', 'role': 'assistant'}]