Specificity of glycopeptide-specific T cells

Area of Science:

• Immunology
• Glycobiology

Background:

• CD4 T cells play a crucial role in adaptive immunity.
• Understanding T cell specificity is key to developing effective vaccines and therapies.
• Glycopeptides present unique challenges for T cell recognition.

Purpose of the Study:

• To investigate the fine specificity of glycopeptide-specific CD4 T cells.
• To determine the structural requirements for T cell recognition of the disaccharide galabiose.
• To differentiate between T cell populations recognizing conformational versus direct molecular epitopes.

Main Methods:

• Conjugation of the disaccharide galabiose to hen egg lysozyme (HEL) peptides.
• Generation and selection of T cell hybridomas from immunized CBA/J mice.
• Assessing T cell hybridoma reactivity to modified peptides and disaccharides.

Main Results:

• T cell hybridomas specifically recognized galabiose, not cellobiose.
• T cell reactivity was dependent on the position of galabiose conjugation on the peptide.
• Acetylation of galabiose abolished T cell stimulation, indicating the importance of hydroxyl groups.

Conclusions:

• Two distinct sets of glycopeptide-specific CD4 T cells exist.
• One set is likely induced by conformational changes in MHC-bound peptides.
• The second set exhibits specificity for both the disaccharide and peptide antigen.