Human T-cell subset requirements for the production of specific anti-influenza virus antibody in vitro

Rearrangements of genes for the antigen receptor on T cells as markers of lineage and clonality in human lymphoid neoplasms

The T alpha and T beta chains of the heterodimeric T-lymphocyte antigen receptor are encoded by separated DNA segments that recombine during T-cell development. We have used rearrangements of the T beta gene as a widely applicable marker of clonality in the T-cell lineage. We show that the T beta genes are used in both the T8 and T4 subpopulations of normal T cells and that Sézary leukemia, adult T-cell leukemia, and the non-B-lineage acute lymphoblastic leukemias are clonal expansions of T cells. Furthermore, circulating T cells from a patient with the T8-cell-predominantly lymphocytosis associated with granulocytopenia are shown to be monoclonal. Finally, the sensitivity and specificity of this tumor-associated marker have been exploited to monitor the therapy of a patient with adult T-cell leukemia. These unique DNA rearrangements provide insights into the cellular origin, clonality, and natural history of T-cell neoplasia.

HLA class II restriction governing cell cooperation between antigen-specific helper T lymphocytes, B lymphocytes and monocytes for in vitro antibody production to influenza virus

To study HLA class II compatibility requirement for in vitro antibody production to influenza virus, semipurified T lymphocytes, B lymphocytes and monocytes from HLA-typed responder donors were used. The presence of the three subpopulations was required for antibody production while a mixture of only two of those was ineffective. When using fresh T lymphocytes which exert an allogeneic suppressive effect and may also exhibit allogeneic helper activity, it was not possible to conclude an HLA class II-linked restriction of T-B cell cooperation although there was a suggestion of it. However, a grown H3 hemagglutinin-specific T cell line (L2), previously shown to be restricted by HLA-DR molecule (DR1) for interaction with antigen-presenting cells and devoid of allogeneic reactivity, exerts an HLA class II-restricted helper activity. This was demonstrated by various combinations of HLA-DR semi-compatible or incompatible B lymphocytes and/or monocytes with L2 T cells. The restriction element was identified as an HLA-DR determined since HLA-DC-compatible, HLA-DR-incompatible B lymphocytes were not helped by L2 T cells. In addition, monoclonal anti-HLA-DR but not anti-HLA-DC antibodies directed to the relevant specificity did inhibit the antigen-specific helper activity. We present evidence that not only T monocyte but also T-B and/or T-B-monocyte interactions are HLA class II restricted.

Antigen-specific human B-cell responses: modulation by immunoregulatory T-cell subsets

In vitro T-cell requirements for and modulation of human B-cell responses were studied in individuals immunized in vivo to the protein antigen keyhole limpet hemocyanin or tetanus toxoid. T cells were required for antibody synthesis in both antigen-driven and pokeweed mitogen (PWM)-driven cultures. T cells were separated into T4+ and T8+ subpopulations using monoclonal antibodies, and their modulation of antibody synthesis was studied. T4+ cells functioned as helper cells in both antigen-driven and PWM-driven cultures in a dose-dependent manner. Whereas T8+ cells suppress both total and specific immunoglobulin secretion in PWM-stimulated cultures, in antigen-stimulated cultures T8+ cells do not suppress unless activated by another cell population present in peripheral blood mononuclear cells (PBMNC). This cellular requirement was further investigated by prestimulation of cells prior to addition to optimally stimulated antigen-driven cultures of PBMNC or B cells, monocytes, and helper T cells. No suppression of these optimally stimulated cultures was seen when T8+ cells were precultured with antigen or PWM. However, after 3-5 days preculture of total T cells with PWM or antigen and then selection of T4+ cells, these cells were able to induce fresh autologous T8+ cells to suppress optimally stimulated antigen-driven cultures. Addition of a precultured mixture of T8+ cells with 20% T4+ cells also resulted in antigen-induced suppression. These data indicate that T8+ cells can suppress antigen-driven cultures but require the presence of preactivated T4+ cells for induction of this suppression of antigen-specific T-cell-dependent human B-cell responses.

Specific anti-influenza virus antibody production in vitro by lymphocytes from a subset of patients with hypogammaglobulinemia

Specific anti-influenza virus antibody production in vitro was studied in peripheral blood mononuclear cells from 17 patients with hypogammaglobulinemia. Cells obtained from 6 of 12 patients with common variable hypogammaglobulinemia produced anti-influenza virus antibody, predominantly of the IgM isotype, when cultured in vitro with type A influenza virus. No antibody was produced in vitro, however, by cells from either of two patients with Bruton's type X-linked hypogammaglobulinemia or by cells from any of three patients with X-linked hypogammaglobulinemia and isolated growth hormone deficiency. These studies demonstrate that peripheral blood mononuclear cells from a subset of patients with common variable hypogammaglobulinemia retain the potential to produce specific antibody in response to antigenic stimulation.

Limiting dilution analysis of Epstein-Barr virus-induced immunoglobulin production by human B cells

The Epstein-Barr virus (EBV) is a herpes virus that has the capacity to infect human B cells and to induce them to secrete immunoglobulin (Ig). In the current experiments, Poisson analysis of limiting dilution cultures has been used to study the activation of human peripheral B cells by the B95-8 strain of EBV. Under the culture conditions used, 0.2-1% of peripheral blood B cells were activated by EBV to secrete IgM or IgG. In addition, when multiple replicate cultures containing limited numbers of B cells were tested for IgM and for IgG production, the precursors for IgM and IgG segregated independently; thus, individual B cell precursors matured into cells secreting IgM or IgG but not both classes of Ig. Additional experiments using limiting dilutions of EBV were undertaken to study the viral requirements for B cell activation. These studies indicated that B cell activation by EBV to produce Ig was consistent with a "one-hit" model and inconsistent with a "two-hit" model. Taken together, these results indicate that infection by one EBV virion is sufficient to induce a precursor peripheral blood B cell to secrete Ig and that only one isotype of Ig is then secreted.