| •
|
Combined immunodeficiency comprises a heterogeneous group of disorders, characterized by lack of T cell-mediated immunity
and impaired B cell function.
|
| •
|
Combined immunodeficiency has most often an early onset, frequently with protracted diarrhea, interstitial pneumonia, recurrent
or persistent candidiasis, and failure to thrive.
|
| •
|
Infections are sustained by intracellular pathogens (especially Pneumocystis jiroveci), viruses, bacteria, and fungi.
|
| •
|
Use of live vaccines and of unirradiated blood products is highly contraindicated in infants with severe combined immunodeficiency
(SCID).
|
| •
|
Maternal T cell engraftment is common in SCID. It may cause “graft-versus-host”-like features, but may also occur without
specific symptoms.
|
| •
|
Family history is of paramount importance. Some combined immunodeficiencies inherited as an X-linked trait, but several autosomal
recessive forms exist, which altogether comprise the majority of cases.
|
| •
|
Lymphopenia is a laboratory hallmark of SCID. However, normal lymphocyte count may be observed in some forms of SCID, especially
if maternal T cell engraftment is present or if the defect allows for residual T cell development.
|
| •
|
Hypomorphic defects may lead to leaky forms of SCID, with residual T cell development. Autoimmune manifestations are common
in this setting.
|
| •
|
Hematopoietic stem cell transplantation is the treatment of choice for SCID, and can cure more than 70% of the affected patients.
Promising results have been achieved with gene therapy, although long-term safety remains an issue.
|