HLA-DRB1 Allelic Combinations Differentially Shape Dendritic Cell Antigen Presentation Enhanced by Tumour Cell Line...

Area of Science:

• Immunology
• Oncology
• Proteomics

Background:

• Tumour-infiltrating lymphocytes (TILs), particularly CD4+ T cells, are crucial for anti-tumour immunity and patient outcomes.
• Understanding CD4+ T cell orchestration of immune responses is vital for developing effective cancer immunotherapies.

Purpose of the Study:

• To investigate how distinct human leukocyte antigen (HLA)-DRB1 allele combinations on dendritic cells (DCs) affect peptide presentation.
• To determine the impact of pulsing DCs with MCF-7 tumour cell line extracts on the immunopeptidome and identify tumour-derived antigens.

Main Methods:

• Analysis of the HLA-II immunopeptidome of DCs from HLA-heterozygous donors.
• Pulsing DCs with MCF-7 tumour cell line protein extract.
• Mass spectrometry-based identification of presented peptides and associated HLA-DRB1 alleles.

Main Results:

• Peptide repertoires presented by DCs are significantly influenced by HLA-DRB1 heterozygosity in an allele-specific manner.
• High-affinity binding alleles (e.g., DRB1*01:01, DRB1*03:01, DRB1*04:04) often dominate peptide presentation, but this is modulated by allelic combinations.
• Pulsing DCs with tumour extracts increased peptide overlap between donors and identified 58 putative tumour-derived proteins, reinforcing allele-specific presentation patterns.

Conclusions:

• HLA-DRB1 allele combinations uniquely shape the presented peptide repertoire, impacting CD4+ T cell recognition.
• Peptide-pulsed DCs present tumour-specific antigens, highlighting potential for personalized immunotherapies.
• Understanding allele-specific antigen presentation is critical for designing targeted immunotherapies to enhance anti-tumour CD4+ T cell responses.