Antigen-specific, major histocompatibility complex-restricted T cell receptors.

Area of Science:

• Immunology
• Molecular Biology
• Structural Biology

Background:

• T cell receptors (TCRs) mediate adaptive immunity by recognizing antigen (Ag) presented by major histocompatibility complex (MHC) molecules.
• Understanding TCR structure is crucial for deciphering T cell recognition and developing immunotherapies.

Purpose of the Study:

• To characterize the structure and composition of Ag/MHC receptors on T cell hybridomas.
• To investigate the molecular basis of Ag/MHC recognition by T cells.

Main Methods:

• Antibody precipitation of T cell hybridoma surface proteins.
• Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to determine molecular weight.
• Isoelectric focusing (IEF) and peptide mapping to analyze protein structure and sequence variation.

Main Results:

• Ag/MHC receptors are heterodimeric glycoproteins of approximately 85 kDa, dissociating into 40-43 kDa acidic and basic chains.
• Both chains exhibit molecular weight heterogeneity and sequence variation between T cell clones, suggesting variable and constant regions.
• Anti-idiotypic antibodies predict Ag and MHC specificity, indicating a single receptor binds both.

Conclusions:

• T cell receptors share structural similarities with immunoglobulins, being disulfide-linked glycoproteins with variable and constant regions.
• A single T cell receptor molecule appears responsible for binding both antigen and MHC.
• These findings provide insights into the molecular mechanisms of T cell recognition.