You Don't Want to Know - S4-E8
Factual error: Dr. House argues that the symptoms of the patient (DIC, bleeding, and multisystem failure) can be explained by the fact that they gave him the wrong type of blood (type AB). House says the reason they could make such a mistake is that they don't test blood type, they test antibodies. Dr. Foreman responds it's because the human body only makes those antibodies when you have that type of blood. This part is incorrect. In fact, it's the exact opposite. You only produce antibodies against the antigens that you DO not have. If you did, your immune system would attack your own red blood cells (RBCs), which would cause autoimmune hemolytic anemia (aiha). For example, if your blood type is A, you make antibody B and vice versa. A person with blood type AB has A and B antigens on the RBCs, but does not produce antibodies A or B and is therefore a universal recipient. Ironically, the latter is also mentioned by Dr. Wilson in a conversation with House earlier in the episode when he says "Of course you're type AB - universal recipient. You take from everybody." House then says that the patient has blood type A, but he's making an extra antibody of type B, which led them to believe he has blood type AB and therefore give him type AB blood. House then deduces that this caused the immunologic reaction, leading to the diagnosis, SLE (lupus), which can cause acquired aiha. It's correct that giving type AB blood to a person with blood type A would cause this, but the first part is wrong. If he is type A, he is supposed to make antibody B, not antibody A, so if he were making an extra antibody, it would be antibody A, not antibody B. (00:38:20)