We studied 17 patients with transient hypogammaglobulinemia of infancy to define the immunologic defect responsible for this disorder. The number of circulating B cells in these patients was normal, as was the ability of the B cells to synthesize immunoglobulins when stimulated with Epstein-Barr virus, a direct B-cell activator. However, the capacity of the B cells to synthesize IgG in response to pokeweed mitogen, a T-cell-dependent B-cell activator, was depressed. Experiments with cultured lymphocytes indicated that excess suppressor-cell activity was not present in these patients, but that their T cells were deficient in providing help to B cells from their normal parents. A numerical deficiency in T4-positive (T4+) helper cells was found. Patients who had recovered from the disorder had a normal number of T4+ helper cells. Our results indicate that a numerical, as well as a functional, deficiency in helper T cells underlies the deficiency in IgG production in transient hypogammaglobulinemia of infancy.

The immunologic and virologic status of a chimpanzee inoculated with multiple isolates of the human immunodeficiency virus type 1 (HIV-1) were assessed over 57 months to determine whether prolonged thrombocytopenia and CD4+ lymphocytopenia observed in the animal might be associated with long-term HIV infection. Although the chimpanzee showed no signs of disease, it lost both CD4+ (as low as 134 cells/microliter) and CD8+ lymphocytes approximately 30 months after initial infection, followed by thrombocytopenia that has persisted for greater than 2 years. Lymphopenia and thrombocytopenia were preceded by or coincided with the appearance of antibodies cross-reactive with histone H2B and decreased levels of complement component C4; an eightfold decrease in HIV-specific antibody titers; the inability of CD8+ lymphocytes to suppress virus replication; impaired proliferative responses to T cell mitogens; and the isolation of cell-free HIV from plasma. These data suggest that, given sufficient time, HIV-infected chimpanzees may develop disease.