Combined Response I. At first glance, the specific immune system might appear to play a less- important role in immunity than the nonspecific. However, if you look at the combined response of both branches to bacteria or viruses, it's clear that the specific branch does a lot to activate the non-specific. Describe several ways in which this happens for each type of pathogen. 2. TH cells don't have any weapons at all. Yet they are one of the most important cells in the immune system. Why?.