Effects of glomerular macrophages on mesangial cells in rat serum sickness glomerulonephritis: a comparison of histological and co-culture studies.

Effects of glomerular macrophages on mesangial cell proliferation at different stages of experimental serum sickness nephritis (SSN) in the rat were examined using a direct co-culture system. The results were compared with the manifestations of glomerular tissue at the same points in time during the course of the SSN, especially with regard to glomerular infiltration and glomerular cell proliferation. Macrophages were isolated from the glomeruli at different points in time during the course of the SSN. While the number of glomerular macrophages increased during the sensitization, the proliferating cell nuclear antigen/cyclin positivity of the glomerular tissue was increased after cessation of the antigenic sensitization. The effect of macrophages on mesangial cell proliferation was relatively diminished during the sensitization but was augmented thereafter. Proliferating cells were mostly attached by macrophages, suggesting the importance of the proximity of macrophages for mesangial proliferation. These results suggest that mesangial cell proliferation is largely influenced by macrophage function variability in the glomeruli during the course of SSN.