Talk to most people about grammar and you’re likely to hear a lot about little issues that are, essentially, language trivia — matters like when to use “whom,” how to use “between” and whether you can ...

Complement component 3, often called C3, is an essential protein of the immune system. This protein plays a vital role in the body’s innate immune system, providing the first line of defense against ...

A complement blood test measures how well complement proteins in your blood support immune defense. The complement system helps antibodies fight germs and clear foreign substances. Complement testing ...