severe combined immunodeficiency disease
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a deficiency of immune response or a disorder characterized by deficient immune response; classified as antibody (B cell), cellular (T cell), or combined deficiency disorders. Antibody immunodeficiencies are marked by hypo- or dysgammaglobulinemia, recurrent bacterial otitis media, and sinopulmonary infections. Cellular immunodeficiencies are characterized by recurrent low-grade or opportunistic infections, by graft-versus-host disease or reaction after blood transfusions, and by severe disease after immunization with live vaccines. See also acquired immunodeficiency syndrome.
common variable immunodeficiency (CVID) a heterogeneous group of disorders characterized by hypogammaglobulinemia, decreased antibody production in response to antigenic challenge, and recurrent pyogenic infections, often associated with hematologic and autoimmune disorders. Most patients have normal numbers of circulating B cells but lack plasma cells and appear to have an intrinsic defect of B cell differentiation. However, two other forms are also recognized: that due to a disorder of T lymphocyte regulation and that due to production of autoantibodies against T and B lymphocytes.
severe combined immunodeficiency (SCID) any of several rare congenital diseases, some of autosomal recessive and some of X-linked inheritance, in which both humoral and cell-mediated immunity fail to develop normally and T lymphocytes are absent or nearly so. In some forms, B lymphocytes are also absent. Early diagnosis is essential to prevent opportunistic infections. Persistent diarrhea, chronic mucocutaneous candidiasis, and failure to thrive may occur in infancy. Blood transfusions can result in graft-versus-host disease and routine vaccinations in fatal infection. Unless immune function is restored by a matched-donor bone marrow or fetal tissue transplantation or the patient is kept in complete isolation, the prognosis is poor.
severe combined immunodeficiency disease (SCID)
Etymology: L, servus, slave
an abnormal condition characterized by the complete absence or marked deficiency of B cells and T cells, with the consequent lack of humoral and cell-mediated immunity. The disease occurs as an X-linked recessive disorder affecting only males and as an autosomal-recessive disorder affecting both males and females. It results in a pronounced susceptibility to infection and is usually fatal. The precise cause of SCID is not known, but research indicates that the disease may be caused by a cytogenic dysfunction of the embryonic stem cells that normally differentiate into B cells and T cells. The affected individual consequently has a very small thymus and little or no protection against infection.
observations Pronounced susceptibility to infection usually becomes obvious 3 to 6 months after birth, when maternal immunoglobulin reserves begin to diminish. Diagnosis is difficult because B cell immunity dysfunction is hard to detect in any individual until 5 months after birth, when immunoglobulin levels should reach a low point. Infants with SCID commonly fail to thrive and have a variety of complications, such as sepsis, watery diarrhea, persistent pulmonary infections, and common viral infections that are often fatal. Some infants with SCID have mild infections and low-grade fevers that last for several months while the infant uses maternal immunoglobulin stores. These conditions generally become fatal when maternal antibodies are totally depleted. Some of the more obvious symptoms after the infant has used most of the maternal immunoglobulin stores are cyanosis, rapid respirations, and normal chest sounds with an abnormal chest radiographic picture. Maternal immunoglobulin G (IgG) is persistent, and gram-negative infections usually do not appear until after the sixth month of life. Normal infants less than 5 months of age have very small amounts of IgM and IgA, and normal IgG levels reflect only maternal IgG. The combination of several symptoms may confirm the diagnosis of SCID, including the absence or severe reduction of T cell and B cell immunity; a lymph node biopsy result that shows no lymphocytes, plasma cells, or lymphoid follicles; and no skin reaction to swabbing with dinitrochlorobenzene. Most infants with SCID die from severe infection within 1 year after birth.
interventions Treatment of SCID seeks to develop the immune system and to prevent infection. The only satisfactory treatment available to correct immunodeficiency is histocompatible bone marrow transplantation, but that may cause a graft-versus-host reaction, thus increasing the risk of infection and fatal consequences. Maintained enclosure in a completely sterile environment has prolonged the life of some infants with SCID, but this option is not successful if the infant has already had recurring infections.
nursing considerations Supportive treatment is the primary approach in caring for the SCID patient. The nurse tries to promote an encouraging atmosphere of growth and development while providing the parents with emotional support in the face of the nearly inevitable early death of their child. The infant must remain in strict protective isolation and benefits from diligent nursing attention, frequent parental visits, and gifts of toys, which should be the kind that can be easily sterilized.
severe combined immunodeficiency disease,
A syndrome marked by gross functional impairment of both humoral and cell-mediated immunity and by susceptibility to fungal, bacterial, and viral infections. Although the disorder may occur sporadically, most commonly it is an X-linked or autosomal recessive trait. If untreated, infants rarely survive beyond their first year. It is important that the disease be recognized early and that patients not be given live viral vaccines or blood transfusions. The immunologic defects may be repaired by stem cell transplantation. The optimal donor is an HLA-identical family member of the patient.Synonym: reticular dysgenesis