Henoch schonlein purpura is characterized by deposition of which of the following antibodies in the blood vessels?: (A) IgA, (B) IgG, (C) IgD, (D) IgM
Answer is A. Henoch-Schonlein purpura

Henoch - Schonlein purpura is vasculitis of small vessels (capillaries, venule or arterioles) and characterized by deposition of IgA in the wall of involved vessels.
H.S. purpura is characterized by a tetrad of purpura, arthritis, glomerulonephritis, and abdominal pain. Gross hematuria is seen in 20-30% of cases.
All changes resulting from the deposition of circulating immune complexes, containing IgA and complement on the endothelium of the blood vessels throughout the body and within the glomerular mesangial regions.
Diagnosis is confirmed by the presence of palpable purpura with normal platelet count along with one or more of the following: abdominal pain, arthralgia/arthritis and mesangial deposition of IgA.
Renal manifestations usually start at the onset or within 3 months of onset of other symptoms