Lymphocyte function-associated antigen 1 (LFA-1) contains sulfated N-linked oligosaccharides

Area of Science:

• Immunology
• Glycobiology
• Cell Biology

Background:

• Lymphocyte function-associated antigen 1 (LFA-1) is crucial for T lymphocyte responses.
• The glycosylation of LFA-1, a key immune molecule, remains largely uncharacterized.
• Understanding LFA-1 glycosylation is vital for elucidating its function in immune cell interactions.

Purpose of the Study:

• To investigate the oligosaccharide structures of murine LFA-1.
• To determine the nature and location of glycosylation on LFA-1 alpha and beta chains.
• To examine the cell-type specific expression of sulfated LFA-1.

Main Methods:

• Metabolic labeling of LFA-1 with radioactive isotopes ([35S] sulfate, [3H]glucosamine, [3H]mannose, [3H]fucose).
• Immunoprecipitation and isolation of LFA-1 alpha and beta chains.
• Tryptic-chymotryptic digestion and glycopeptide analysis using HPLC.
• Enzymatic digestion with N-glycosidase, Endo F, Keratanase, and endo-beta-galactosidase.
• Analysis of LFA-1 expression on various murine cell types.

Main Results:

• Both LFA-1 alpha and beta chains incorporate sulfate, glucosamine, mannose, and fucose.
• Five major N-linked glycopeptides were identified on each LFA-1 chain.
• The majority of glycosylation and sulfation on LFA-1 are N-linked oligosaccharides.
• Sulfated N-acetyllactosamine sequences are present on LFA-1.
• Sulfated LFA-1 is predominantly expressed on thymocytes and splenic T cells.

Conclusions:

• Murine LFA-1 possesses complex N-linked glycosylation, including sulfated N-acetyllactosamine structures.
• Glycosylation patterns of LFA-1 vary depending on the cell type, with significant sulfation observed on T lymphocytes.
• These findings provide novel insights into the post-translational modifications of LFA-1 and their potential role in immune cell function.