The spleen in malaria: the role of barrier cells.

I believe that my laboratory has developed a construct of the spleen useful in understanding its range of normal and pathologic functions. The elements in the construct include recognition of an anatomically open vasculature with the interposition of reticular cell-reticular fiber filtration beds between terminal arterial vessels and proximal venules. The central function of the spleen, moreover--selective clearance of cells, microbes and other particles from the blood--depends upon these filtration beds. Such functions of the spleen as phagocytosis, immunologic reactivity, hematopoiesis, and blood cell storage derive from its clearance capacities. The reticular filtration beds offer but modest levels of basal clearance. The wide ranges of filtration that characterize the stressed spleen depend upon arming or augmenting the basic reticular filtration beds with responsive cells which can rapidly appear, and rapidly disappear. These include macrophages, salient phagocytic cells of rich repertoire, which have been accorded the major, even exclusive, role in splenic clearance. But other stromal cells participate in splenic clearance. I have identified a system of fibroblastic, contractile, granulated cells which fuse to form complex, branched syncytial sheets which, deployed as diverse barriers, augment the basic reticular filtration beds. Hence, I term these cells barrier cells. Barrier cells effectively interact with macrophages, reticular cells, other stromal and blood cells, contributing to the extraordinary range of splenic clearance capacities. Barrier cells may be elicited by a variety of infectious processes, damaged blood cells and hematopoietic factors. Interleukin-1-alpha evokes a strong barrier cell response, and may be the common denominator in splenic stress, stimulated by activated macrophages.(ABSTRACT TRUNCATED AT 250 WORDS)