Severe Combined Immunodeficiency Disease (SCID)

Severe combined immunodeficiency disease (SCID) is characterized by the absence of both humoral and cellular immunity. The terms “lymphopenic agamma-globulinemia of the Swiss type”, an autosomal recessive form of the disease and “x-linked lymphopenic agamma-globulinemia”, which, as the name implies, can follow either the mode of inheritance, are used to describe this disorder.

pathophysiology
The exact cause of SCID is unknown. Theories include
1. defective stem cell that is unable to differentiate into B or T cells
2. Defect organs responsible for the differentiation process, primarily the thymus and lymphoid complex, or
3. enzymatic defect that suppresses the function of lymphocytes.

The consequence of immunodeficiency is the overwhelming susceptibility to infection and the graft-vs-host reaction. The latter occurs when any histo-incompatible tissue from an immunocompetent donor is injected into an immunodeficient recipient. Due to its immunodeficiency, the body cannot refuse foreign incompatible tissue. Therefore, antigenic donor cells attack the host tissue. Graft versus host reaction is a serious complication in the only known SCID treatment, bone marrow transplantation.

Clinical manifestations
Obviously, the most common manifestation is susceptibility to infection at an early stage of life, most often for 3 months, when maternal immunity is low. In particular, the disorder in children is characterized by chronic infection, the inability to fully recover from the infection, frequent reinfection and infection by unusual agents. In addition, the story does not detect a logical source of infection. The inability to thrive is a consequence of persistent disease.

It is expected that if the child gets someone else’s tissue, such as blood supplements, there will be signs of a graft versus host reaction, such as fever, skin rash, alopecia, hepatospenomegaly and diarrhea. Since the reaction requires 7 to 20 days for tissue damage to become apparent, symptoms may be mistaken for an infection. However, having a graft-vs-host reaction increases the child's susceptibility to suppressive infection and, therefore, is a serious complication.

Diagnostic evaluation
The diagnosis is usually based on a history of recurrent, severe infections from early childhood, a family history of recurrent, severe infections from early childhood, a family history of the disorder and specific laboratory data that include lymphopenia, no lymphocyte response to antigens, and no plasma cells in the bone marrow. Documentation of immunoglobulin deficiency is difficult in infancy due to the normally delayed response of the infant to the production of its own immunoglobulins and the transfer of immunoglobulin G.

Therapeutic management
The only final treatment is a histo-compatible bone marrow transplant, the ideal donor is an identical twin, because human lymphocytic antigens (HLA) are exactly the same. The second best choice is a sibling. The procedure consists of the aspiration of several bone marrow samples from the donor and intravenous intravenous administration to the brain. However, bone marrow transplantation is usually carried out in medical centers, where control measures are available after a transplant, such as a sterile environment and other specialized means. Since the host’s immunological system is incompetent, graft rejection is not a problem. However, graft-vs-host reaction is always possible in a non-identical double graft, and once this happens, little can be done to reverse the process.

Other SCID approaches provide passive immunization with immune globulin and keep the baby in a sterile environment. The latter is effective if it was introduced before the appearance of any infectious process in the infant. Other studies related to transplant procedures include non-identical HLA bone marrow transplants and liver transplantation or thymus graft transplants. Nevertheless, the results are still uncertain, although they offer potential hope for future children to build on the disorder.