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Treatment of combined T and B-cell immunodeficiencies
Last reviewed: 04.07.2025
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Principles of treatment of severe combined immunodeficiency
Severe combined immunodeficiency is a pediatric emergency. If SCID is diagnosed within the first month of life, adequate therapy and allogeneic HLA identical or haploidentical bone marrow transplantation (BMT) or hematopoietic stem cell transplantation (HSCT) ensure survival of more than 90% of patients regardless of the form of immunodeficiency. In case of later diagnosis, severe infections develop that are difficult to treat, and patient survival drops sharply.
Immediately after diagnosis of severe combined immune deficiency, children should be kept in gnotobiological conditions (sterile box), in case of infection, intensive antimicrobial, antiviral and antifungal therapy, replacement therapy with intravenous immunoglobulin is carried out. Since BCG vaccination is carried out in the first days of life, children with SCID in most cases are infected, and they develop BCG-itis of varying severity (from local to generalized infection). BCG infection requires long-term intensive anti-tuberculosis therapy. Co-trimoxazole is prescribed for the prevention of Pneumocystis pneumonia. It should be especially noted that if it is necessary to transfuse blood components (red blood cell mass, platelet concentrate), only irradiated and filtered drugs should be used. In case of transfusion of non-irradiated red blood cells and platelets, post-transfusion GVHD develops.
Complete immune reconstitution does not always occur after HSCT. Some patients do not have complete B-cell engraftment and require lifelong replacement therapy with intravenous immunoglobulin, but this condition is usually not an immunological defect incompatible with life.
In families with a history of SCID, prenatal diagnosis is especially important. Even if the parents decide to continue the pregnancy, placing the patients in sterile conditions from birth and early transplantation significantly improve the prognosis. In addition, in several cases of prenatal confirmation of SCID, intrauterine bone marrow transplantation from the father was performed, most of them were successful.
Gene therapy
Due to the lethality of SCID in the absence of HSCT and often incomplete reconstitution during its implementation, patients with severe combined immune deficiency have become the first candidates for gene therapy. To date, it has been performed in 9 patients. At the same time, the two youngest patients in the group after some time developed leukemia-like diseases associated with mutagenesis caused by the transfected vector. In this regard, more effective vectors for use in gene therapy are currently being sought.