Direct interactions between B and T lymphocytes bearing complementary receptors.

Area of Science:

• Immunology
• Cell Biology

Background:

• A specific murine cloned T helper (Th) cell line recognizes conalbumin antigen presented by self I-A molecules.
• Activation of T cell receptors (TCRs) by soluble anti-receptor monoclonal antibodies (mAbs) is an unusual characteristic.

Purpose of the Study:

• To investigate the mechanism of T cell activation by soluble anti-receptor mAbs.
• To explore the interaction between this cloned Th cell line and B cells.
• To understand the role of receptor-receptor interactions in immune repertoire generation.

Main Methods:

• Activation of cloned Th cells with soluble anti-receptor mAbs.
• Limiting-dilution analysis to assess cell growth and activation.
• In vivo immunogenicity studies in mice and rats.
• In vitro co-culture of purified B cells with cloned Th cells.

Main Results:

• The cloned Th cell line is activated, not inhibited, by soluble anti-receptor mAbs.
• This activation does not require accessory cells (APCs), Fc receptors (FcRs), or cell-cell contact.
• The Th cell line is highly immunogenic in vivo, inducing growth-stimulating anti-receptor antibodies.
• The Th cell line directly interacts with B cells, leading to monoclonal antibody (mAb) production in nude mice and stimulating antibody production in vitro.

Conclusions:

• The cloned Th cell line's unique response to anti-receptor antibodies facilitates direct B cell activation.
• This direct Th-B cell interaction serves as a model for receptor-receptor interactions in T and B cell repertoire development.