Severe combined immunodeficiency with B-lymphocytes (T-B+SCID): report of two cases.

Severe combined immunodeficiency (SCID) is a rare pediatric medical emergency in Taiwan. The early diagnosis of infants with SCID is very important because it can save the life of these critical infants. The essential clues important for early diagnosis of SCID patients include positive family history of early infant death, paucity of tonsil and lymphoid tissue, cutaneous fungal infection and lymphopenia. Severe combined immunodeficiency is a heterogeneous group of inherited disorders characterized by the failure of both cellular and humoral immunity. It can be categorized into SCID with B-lymphocytes predominant (T-B+SCID) and SCID with paucity of B-lymphocytes (T-B-SCID), according to the number of B-lymphocytes in the patient's peripheral circulation. We report two male infants with T-B+SCID who had been suffering from severe pulmonary distress with persistent O2 desaturation when they were transferred to our pediatric intensive care unit. Tracing back these infant's family histories, it was discovered that both of them had an elder brother who had died to overwhelming infection within the first year of life, and Pneumocystis carinii pneumonitis (PCP) was confirmed in the elder brother of case 2. After hospitalization, the immune condition of these two infants were evaluated which showed a decrease in T-cell and NK cell number, an increase in B-cell number, and decreased serum levels of all the Igs except IgM, which was elevated in case 1. These were the diagnostic immunological findings for T-B+SCID, which included X-linked SCID and Jak-3-deficient SCID. During hospitalization, severe mucocutaneous candidiasis and PCP were noted and confirmed in case 1 and PCP was highly suspected in case 2. Bone marrow transplantation, the only curable treatment for T-B+SCID at present, could not be performed in these two patients because of their grave clinical condition. Both of them expired due to their progressively downhill pulmonary conditions.