Cytomegalovirus and kidney

This study was conceived to identify specific morphological characteristics associated with cytomegalovirus (CMV) infection of the kidney. 33 patients with manifest CMV infection at autopsy and 32 biopsies of kidney transplants with active or inactive CMV infection were studied. In 8 patients of the autopsy group a CMV infection of the kidney was detected (CMV cells in 3 cases, positive viral tissue culture in 4 cases, positive in-situ hybridization in one case), which was associated with severe dissemination into different organs. In situ hybridization was not superior to ordinary light microscopy in the detection of CMV cells. The biopsies were screened for the presence of glomerulopathy. No association of glomerulopathy with CMV could be found by light microscopy, whereas a significant correlation of glomerulopathy with vascular rejection was demonstrated. No differences as to the incidence of glomerulopathy were found, when non-transplant patients with manifest CMV infection at autopsy were compared with matched controls. With active infection electron microscopy revealed no osmiophilic deposits, but in immunofluorescence tiny IgG deposits were identified within the glomeruli (p less than 0.01). IgM or C3 deposition in the glomeruli was not specifically associated with either CMV infection or vascular rejection. Thus morphological identification of CMV infection of the kidney is difficult, necessitating the detection of CMV cells, positive viral tissue culture or positive in-situ hybridization. Glomerulopathy in light microscopy is associated with vascular rejection and is therefore termed transplant glomerulitis. Tiny IgG deposits may be indicative of CMV infection, although these are not always present.