ZF, your mention of cytokines brings my current area of mucking about.

Cytokines are the chemicals associated with the immune system just as hormones are associated with the endocrine system. The former is to infection what the latter is to stress (I know that is a little simplified).

Prenatal bacterial toxin exposure sensitizes us to future exposure. Even normal immune systems monitor the levels of the bacterial toxins to detect early infections. We react sooner than normal. The reaction is, in part, to produce cytokines.

The body does not want too many cytokines so it regulates them by producing natural steroids such as cortisol. Just as a doctor might give you a shot of steroids to bring down inflammation.

So we have a see-saw effect between the two systems and a shifting tide of cytokines and steroid hormones. Which finally brings me to my point.

Both families of chemicals and their breakdown products function as neurotransmitters!

Now, that's as far as I've gotten so far, but it sure seems relevant to me.