The specificity of T-cell helper factor in man

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• Human T cells stimulated with TT antigen produce a factor that influences B cell activity.
• This factor, termed LMF-TT, induces B cell proliferation and immunoglobulin synthesis.
• The precise nature and function of this T-cell-derived factor require further elucidation.

Purpose of the Study:

• To characterize the T-cell-derived factor (LMF-TT) responsible for B cell activation.
• To investigate the antigen-specific versus polyclonal activation capabilities of LMF-TT.
• To determine the optimal conditions for LMF-TT-mediated B cell mitogenesis and immunoglobulin production.

Main Methods:

• Supernatants from TT-stimulated human T cells were analyzed using Sephadex G 200 chromatography and anti-TT immunosorbent columns.
• B cell activation assays were performed using varying concentrations of LMF-TT, with and without specific antigens (TT, DT).
• B cells from immune and non-immune donors were utilized, and antigen-specific IgG production was quantified.

Main Results:

• LMF-TT induced B cell mitogenesis and IgG synthesis in both TT-immune and TT-non-immune individuals.
• While LMF-TT acts as a polyclonal activator, it preferentially triggers antigen-specific B cells when the cognate antigen is present.
• Antigen specificity of the produced IgG was dependent on the presence of the specific antigen during B cell incubation with LMF-TT.

Conclusions:

• LMF is a nonspecific human T-cell helper factor that functions as a polyclonal B-cell activator.
• In the presence of specific antigen, LMF preferentially activates antigen-specific B cells.
• The study suggests the potential involvement of an additional antigen-specific helper factor.