They usually have a normal phenotype, with some degree of in vivo activation, as shown by the expression of MHC class II molecules and/or the IL-2 receptor. Maternal T lymphocyte numbers range from 10 to several thousand/μl of blood. It is noteworthy that maternal T cells are not found in ADA-deficient patients, possibly because maternal T cells are killed by the raised levels of deoxyadenosine (see below). Circulating maternal T cells are detected in approximately 50% of cases. Maternal T lymphocyte engraftment is frequently detected in SCID patients using molecular tools. The two possible sources of allogeneic cells are maternal lymphocytes and transfusion. Non-infectious clinical manifestations consist mainly of graft- versus-host disease (GVHD) caused by the patients' inability to reject allogeneic cells. It is clear that live vaccine must not be given to children at risk for SCID. Interestingly, three of six patients who received oral attenuated poliovirus had detectable virus in the stools, but none developed poliomyelitis this was probably either because of slow viral replication in transplant recipients or because of protection by maternal immunoglobulins. We have observed BCG infection in 10/28 vaccinated patients (including two with local infection and eight with disseminated involvement of the liver, spleen and lungs), which was fatal in three cases. Live vaccines can also cause life-threatening infections. BLPD has also developed in untreated SCID patients. Some occurred following therapy of SCID (thymic transplant, fetal liver transplant or T-depleted marrow transplant), which was presumably the source of EBV. Thirty-one such cases have been reported. Infection by Epstein–Barr virus (EBV), although rare in this age group, can lead to uncontrolled B lymphocyte proliferative disorders (BLPD) in B(+) SCID patients, similar to that seen in immunosuppressed transplant recipients. Intracellular organisms such as listeria and legionella can cause devastating disease, as can viruses, especially those of the herpes group. Įven common opportunistic organisms such as Pneumocystis carinii and Aspergillus species can cause infections.

Our findings were similar to an American study of 100 infants. The persistence and recurrence of infections in SCID patients rapidly lead to growth impairment and malnutrition.

There are no differences between the various SCIDs, except for an earlier onset of infections in patients with ADA deficiency. Oral candidiasis, persistent diarrhoea with growth impairment and/or interstitial pneumonitis are the most frequent infectious manifestations leading to diagnosis. We reviewed the frequency of infections and the diagnosis in 117 patients with SCID who were referred to our centre. The clinical presentation is fairly uniform and is characterized by early onset of infections, mainly of the respiratory tract and gut.

Severe combined immunodeficiency scid