A rare but interesting (and potentially fatal) type of thrombotic microangiopathy (TMA) called neuraminidase-associated TMA occurs with severe pneumococcal pneumonia or meningitis. Neuraminidase is a protease which cleaves off a specific antigen (Thomsen-Friedreich) on the surface of platelets and endothelial cells, exposing a cryptic antigen to which pre-formed IgM antibodies bind, resulting in TMA and renal failure.
