Cytomegalovirus Pneumonia in Allogeneic Bone Marrow Transplantation: Discussion (1)

Recent advances in the therapy for CMV pneumonia in patients with allogeneic BMTs have shed new light on the pathogenesis of the disease. First, viral titers in the pulmonary tissue have no correlation with the severity of the illness. Therapy with DHPG results in a 99.99 percent reduction of the viral titer but not the high mortality.2 Secondly, prospective trials of combined therapy with GIG and DHPG showed dramatic improvement in the survival rate. Thirdly, clinically significant CMV pneumonia is rare in autologous BMT recipients or in patients with the acquired immunodeficiency syndrome, although the virus is frequently present in the BAL obtained from these patients. These observations suggest that the pathologic process of CMV pneumonia in BMT patients is not solely related to the viral replication. An intense pneumonitis causing morbidity and mortality requires the presence of a competent host immune system.
Grundy et al proposed that CMV pneumonia in patients with BMTs is an immunopathologic disease. According to the hypothesis, the primary pathologic process is due to the activation of the hosts cell-mediated response by a viral antigen. The beneficial effect of GIG in the treatment of this disease is probably due to the blockage of the activation of the host’s immune system by forming an immune complex with the viral antigen.