Antigen-specific helper factor production by immortalized clone of OVA-specific T cells. I. In vitro activity

Antigen-specific helper function of cell-free T cell products bearing TCR V beta 8 determinants

Although the T cell receptor (TCR) alpha beta heterodimer and its encoding genes have been characterized, a cell-free form of this receptor, which is needed for the study of functional or ligand-binding properties of the receptor, has not previously been isolated. When the cell-free supernatant products of activated cloned T helper (TH) cells were found to mediate helper activity with antigen specificity identical to that of intact T cells, experiments were carried out to determine whether this functional activity was mediated by a cell-free form of TCR-related material. A disulfide-linked dimer indistinguishable from the T cell surface alpha beta heterodimer was precipitated from cell-free supernatants of cloned TH cells with F23.1, a monoclonal antibody specific for a TCR V beta 8 determinant. Moreover, when cell-free TH products were bound to and eluted from immobilized F23.1, these affinity-purified materials had antigen-specific and major histocompatibility complex-restricted helper activity that synergized with recombinant lymphokines in the generation of B cell antibody responses. These findings suggest that the factor isolated from T cell supernatants is a cell-free form of the TCR alpha beta dimer.

An arthritogenic lymphokine in the rat

A type II collagen-specific arthritogenic lymphokine has been identified in the rat. Arthritogenic factor (AF) is a 65 kD protein generated in vitro by T cells from rats with collagen arthritis, and it induces an erosive, proliferative synovitis when injected into the knee joint of syngeneic naive recipients. Complement does not appear to be required. These data identify a potential T cell-mediated effector mechanism in this model, and suggest that AF may function in other inflammatory synovial diseases.

Antigen non-specific activities in culture supernatant of ovalbumin-specific, cloned helper T lymphoma

Antigen non-specific activities in culture supernatants from clones of a radiation leukemia virus transformed, ovalbumin-specific helper T lymphoma were studied. After stimulation with ovalbumin-pulsed macrophages, these clones release factor(s) capable of providing carrier-specific help for anti-hapten antibody responses. It was found that in addition to IL 2-like activity, one clone constitutively released a suppressive factor that could inhibit polyclonal growth and differentiation of B cells stimulated with LPS. The factor inhibited activation of both syngeneic and allogeneic B cells directly, rather than via activation of accessory suppressor T lymphocytes. However, upon dilution of the supernatant, B cell growth and differentiation activities were detected. A role for a polyclonal B cell suppressor factor in the overall helper activity of the clone is proposed.