Cytomegalovirus pneumonia as the first manifestation of severe combined immunodeficiency

Szczawinska-Poplonyk, Aleksandra; Jonczyk-Potoczna, Katarzyna; Ossowska, Lidia; Breborowicz, Anna; Bartkowska-Sniatkowska, Alicja; Wachowiak, Jacek

The results of our retrospective analysis indicate that severe, life-threatening respiratory tract infections of viral etiology are the most frequent initial manifestation of severe combined immunodeficiencies. It is worth noting that administration of live attenuated vaccines against Mycobacterium tuberculosis in all children studied as well as against measles, mumps and rubella in the two patients, did not lead to vaccine-associated adverse effects in any of them despite T-cell lymphopenia, posing a high risk of complications. In as many as four of all five of the children studied, we found specific etiology, associated with CMV infection and in one child we documented an hCoV infection [4] . Certainly, such a small study group of children with SCID as a result of the proportional frequency of this primary immunodeficiency in the pediatric population [5] , estimated at about 7% of all PIDs [6] was under investigation, is the major limitation of this review. However, among patients with acquired CMV infection, neonates and infants contribute to the large proportion of the infected Polish population, reaching 50% [7] . The host's immune status governs further viral propagation and CMV-related pathology, including interstitial pneumonia. Cell-mediated immunity is the main defense against CMV disease, including CD4 T helper cells and interferon gam-ma (IFN-γ) and interleukin 2 (IL-2) production, CD8 T cell-mediated cytolytic activity, as well as NK cell cytotoxicity. As inadequate immune response of CD4 T cells is a major factor responsible for lack of immune control of CMV infection, therefore, cytomegalovirus is considered to be a major pathogen in severely immunocompromised individuals as infants with SCID [8] and children with secondary immunodeficiencies, such as recipients of hematopoietic cell transplantation [9, 10] . Significant morbidity and mortality in immunodeficient hosts may result from a primary, congenital or acquired infection, occur as a consequence of reactivation of the latent virus, or infection with a new CMV strain. Severe, occasionally life-threatening disease, which can manifest with viremia, pneumonia, hepatitis, as well as central nervous system pathology may be observed both in congenital and acquired infections [11] .