Natural killer cell clones can efficiently process and present protein antigens

Area of Science:

• Immunology
• Cell Biology

Background:

• Natural killer (NK) cells are lymphocytes of the innate immune system.
• Their role as antigen-presenting cells (APCs) is not fully understood.
• NK cells express various surface markers, including CD2, CD3, CD56, and variable CD16.

Purpose of the Study:

• To investigate the capacity of NK cell clones to function as APCs.
• To determine the range of antigens that NK cells can process and present.
• To explore the correlation between NK cell activation and their APC function.

Main Methods:

• NK cell clones from three donors were isolated and characterized.
• Tetanus toxoid (TT), Der p I allergen, and Mycobacterium leprae peptides were used as antigens.
• Antigen presentation was assessed using Ag-specific T cell clones.
• Class II HLA restriction was evaluated.
• NK cell populations (freshly isolated, IL-2 activated, in vitro expanded) were tested.

Main Results:

• NK cell clones efficiently processed and presented TT to T cells in a class II HLA-restricted manner.
• NK cells also presented the Der p I-derived peptide and a specific M. leprae peptide.
• The ability of NK cells to act as APCs correlated with their expression levels of class II HLA.
• Whole M. leprae antigen presentation was not observed.

Conclusions:

• NK cell clones possess significant antigen-presenting cell capabilities.
• NK cells can process and present various soluble proteins and peptides.
• The efficiency of NK cell APC function is linked to class II HLA expression and antigen type.