Transient T-cell abnormality in a selective IgM-immunodeficient patient with Brucella infection.

We describe here one 9-year-old female patient with an unusual form of selective IgM and CD4+ (OKT4+) helper/inducer T-cell immunodeficiency associated with Brucella infection. During the acute phase of Brucella infection, the percentage of infection. During the acute phase of Brucella infection, the percentage of peripheral blood lymphocytes (PBL) displaying OKT3+, OKT11+, and OKT4A+ phenotypes was decreased, and that of the OKT8+ cell was increased. These phenotypic T-cell abnormalities disappeared after antibiotic therapy in a 5-week period. However, the marked deficiency of CD4+ T cells and the IgM deficiency present during the acute phase of illness remained after recovery from illness. In vitro immunoglobulin production experiments during the acute phase of illness demonstrated that the patient's T cells lacked the capacity to provide helper/inducer function for normal B-cell differentiation to secrete IgM. The patient's T cells were also shown to possess IgM-specific suppressor cell activity on normal B- and T-cell differentiations. Thus impaired T-cell function was shown to be responsible for IgM-deficient antibody production. Defective interleukin 2 receptor expression and production by the patient's PBL in response to mitogenic stimulation also were present, indicating a severe defect in the patient's T-cell function.