Rat macrophages: membrane glycoproteins in differentiation and function

Summary: Macrophages (mφ) play a crucial role in the immune system. The rat offers unique advantages for studying the biology of mφ. Firstly, monoclonal antibodies (mAb) against many rat mφ surface glycoproteins have become available. These have not only demonstrated a considerable heterogeneity among mφ, but have also allowed the characterization of various mφ surface molecules in terms of structure, expression regulation and function. Furthermore, substantial numbers of rat mφ can be isolated from various sites (e.g. blood, peritoneal cavity, lung and other tissues), enabling proper molecular and functional analysis of these mφ populations. Finally, a number of (unique) experimental models for human diseases have been developed in the rat, making possible the evaluation of the involvement of mφ in pathogenesis. For this, a method for the selective elimination of mφ from various tissues in vivo has proven very useful. Here, we will review the contribution that the rat has made to understanding the immunobiology of mφ. In particular, we will discuss the surface (glyco)proteins on rat mφ in differentiation and function, and the involvement of mφ in rat models of disease.