I believe it means a normal liver cell - capable of reactions as composed to dead or dying.
oops -- as compared to dead!
Maybe I should just shut up. An hepatocyte is a liver cell. Reactive may mean that it is reactingto something (and outside chemical or perhaps the hepatitis virus). I could not find a good definition of "reactive hepatocyte." Maybe someone else can come up with a better definition. Perhaps if you gave me the whole sentence...