The most significant component in managing CMV infection is cell-mediated immunity. CMV infection has a high prevalence in immunocompromised patients. After primary infection or reactivation of latent illness, CMV-specific CD4+ and CD8+ lymphocytes play a crucial role in immune defense. CMV pneumonitis is more likely among bone marrow transplant recipients who do not generate CMV-specific CD4+ or CD8+ cells, according to studies. There have also been no occurrences of CMV pneumonia reported in allogeneic marrow transplant recipients who had CMV-specific CD8+ cells infusions.