Macrophages and granuloma.

The recent problems concerning macrophages (Mφ) and granuloma are summarized as follows.A Granuloma is a specific form of chronic inflammatory processes, which is defined as an organized collection of Mφ and/or their modified cells. Its basic structures are those of mature granuloma by mature Mφ, epithelioid cell granuloma by epithelioid and Langhans' giant cells and foreign body type granuloma by foreign body giant cells. In the granuloma formation, various cytokines such as MIF, MCF, MFF, IL-1 and TNFa may be necessary for an aggregation of Mφ at the initial stage. Epithelioid cell transformation of Mφ depends on various factors such as cellular immunity, some of immune complexes and MDP as a bacterial cell component. According to epithelioid cell transformation, Mφ may increase the autocrine and mutual adhesive properties instead of phagocytic activity. In some organs such as the liver, a granuloma may consist of heterogeneous Mφ which consist of Kupffer cells, exudative Mφ and monocytes. In addition, the formation of infectious granulomas may be influenced by the functional specificities of each organ.