What are some immunological diseases that are bad?

SCID, ANAPHYLAXIS. Very broad question! the immune system can be nearly missing when you are born, that's called severe combined immune deficiency, and usually requires a bone marrow transplant. Lupus is a chronic disease that is also difficult to have and live with, but not always fatal like untreated scid. Even the most severe allergic reactions, called anaphylactic shock, are "bad immunologic" diseases. Lots are.