Pulmonary Dysfunction Is Common during a Cytomegalovirus Infection after Renal Transplantation even in Asymptomatic Patients:Possible Relationship with Complement Activation

In 24 patients with a cadaveric renal allograft, aerial measurements after transplantation were made of the diffusing capacity for carbon monoxide (DLCO) together with aerial measurements of C3d, the stable conversion product of the complement factor C3, and determinations of the anaphylatoxin C3a. Twelve patients were studied during an active cytomegalovirus (CMV) infection, and 12 patients were studied during allograft rejection or during a stable phase after renal transplantation (control subjects). No patient had pulmonary symptoms nor abnormal chest radiographs or arterial blood gas determinations. During an active CMV infection, DLCO was significantly reduced compared with the measurements made during allograft rejection or during a stable phase altar renal transplantation. This was true both with (p < 0.01) and without (p < 0.011) correction for the hemoglobin concentration. Serum C3d levels were Increased in 8 of the 12 patients with a CMV infection, but not in any of the patients in the control group. In 8 patients with a CMV infection, measurements were made of the anaphylatoxin C3a, and were found to be significantly higher than the levels In the control population (p < 0.01). We conclude that our data are consistent with pulmonary dysfunction In every patient with an active CMV Infection. The concomitant findings of complement activation and formation of anaphylatoxins suggest a causal relationship of the complement activation and a decreased DLCO, although further studied are warranted to determine the exact role of complement in the pulmonary events during an active CMV Infection after renal transplantation. Serial measurements of DLCO with this simple bedside method can be of help In the sometimes difficult differential diagnosis between CMV Infection and allograft rejection. Furthermore, the patients with the greatest drop in DLCO might prove to be the patients who are at greatest risk to develop an overt CMV pneumonitis