Since microbicidal activity is one of the properties of macrophages, they provide rapid protection prior to T and B cell mediated activities, but their activity is non specific and multidirectional.
In addition to CMI they take part in initiation of T cell activity by processing and presenting the engulfed antigen to TH cells. Macrophages and their products are important not only for immune response and inflammation but also for repair of damaged tissues.
Pathology related with CMI:
Cell mediated immunity is intended to protect the body from the invading pathogens but under certain circumstances the protective action or hyper action of CMI results in pathological conditions.
For example excessive release of cytokines particularly TNFa can lead to shock syndromes, hemorrhagic necrosis and necrosis within the sites of cell mediated response. The developed pathology during the CMI action may obstruct the function of the near by tissue.
Some times it may lead to fatal action for instance granuloma developed adjacent to the nerve cells may block nerve function. If granuloma develops in brain or retina it may result in certain functional abnormalities. Autoimmune diseases such as rheumatoid arthritis, psoriasis, multiple sclerosis etc. are due to chronic tissue damage caused by CMI.