Hyper-IgE syndrome is characterized by markedly elevated serum IgE levels, a rash that resembles atopic dermatitis, eosinophilia, and staphylococcal abscesses of the skin, lungs, joints, and viscera (see Table 73-3). Infections with H. influenzae type b, Candida, and Aspergillus also may occur. These patients have coarse facial features, develop osteopenia, and may have giant pneumatoceles in the lungs after staphylococcal pneumonias. Although serum IgG, IgA, and IgM levels are normal, humoral immune responses to specific antigens are reduced, as is cell-mediated immunity. Long-term treatment with antistaphylococcal medications is indicated, and immunoglobulin replacement therapy may be helpful. Most patients have an autosomal dominant form of inheritance, whereas some patients appear to have an autosomal recessive inheritance. Defects in the TYK2 and DOCK8 genes have been found in a patient with an autosomal recessive hyper-IgE syndrome, and defects in the STAT3 (signal transducer and activator of transcription 3) gene were identified in autosomal dominant hyper-IgE syndrome.
The approach to therapy of lymphocyte disorders depends on the diagnosis, clinical findings, and laboratory findings (Table 73-4). When immunodeficiency is suspected and while the evaluation is in process, all blood products need to be irradiated and negative for cytomegalovirus. Lymphocytes present in blood products can cause fatal GVHD in patients with SCID. Cytomegalovirus infection can be fatal in an immunodeficiency patient undergoing stem cell transplantation. Live virus vaccines should be withheld from patients and household members until a diagnosis is established.
Infections should be treated with appropriate antibiotics;prophylactic antibiotics can be used to prevent recurrent infections, provide a better quality of life, and decrease possible consequences. Antibiotic prophylaxis can be provided withonce-daily administration of trimethoprim-sulfamethoxazole or amoxicillin at one half of the total daily therapeutic dose.Patients with severe T-cell deficiencies should receive prophylaxis against Pneumocystis and fungi until treated withstem cell transplantation. Patients with milder forms of antibody deficiency diseases may benefit from vaccination with protein-conjugate vaccines to H. influenzae type b and S. pneumoniae, assaying post vaccination titers at least 1 monthlater. These vaccines are administered routinely to youngchildren; older children and adults with antibody deficiencysyndrome should also receive them to generate protectiveantibody levels.