Is it reasonable to use full word and abbreviation in parenthesis in a chapter title? Can I use full word plus its abbreviation in parenthesis in a chapter title?
here is my case:

Chapter 2
Human Immune System (HIS)

is it correct? Is there any differences if the the full word have appeared before in the previous chapter content.
I can not say this is incorrect, but it is probably unorthodox. If there are no strong reason to put an abbreviation in the title, you may wish to introduce it in the first sentences of the chapter itself.