Human keratinocyte induction of rapid effector function in antigen-specific memory CD4+ and CD8+ T cells

Area of Science:

• Immunology
• Dermatology
• Cell Biology

Background:

• The role of human keratinocytes in antigen presentation to T cells remains controversial.
• Previous research suggested keratinocytes might induce T cell hyporesponsiveness rather than activation.
• The capacity of keratinocytes to process antigens for MHC class I and II presentation was unclear.

Purpose of the Study:

• To investigate the ability of human keratinocytes to process and present antigens to memory T cells.
• To determine if keratinocytes can induce functional responses in CD4+ and CD8+ T cells.
• To explore the implications for cutaneous disease pathogenesis and transcutaneous delivery.

Main Methods:

• Utilized peptides, proteins, and recombinant expression vectors as antigen sources.
• Assessed keratinocyte antigen processing and presentation capabilities.
• Measured T cell functional responses, including cytokine secretion and target cell lysis.

Main Results:

• Keratinocytes efficiently processed and presented protein antigens to CD4+ T cells, leading to Th1 and Th2 cytokine secretion.
• Antigen presentation by keratinocytes to CD4+ T cells required HLA class II and ICAM-1, inducible by IFN-gamma.
• Keratinocytes presented viral or exogenous peptides to CD8+ T cells, resulting in cytokine production and lysis.
• T cell lines stimulated by keratinocytes maintained their functional capacity.

Conclusions:

• Human keratinocytes are capable of efficiently processing and presenting antigens to both CD4+ and CD8+ memory T cells.
• Keratinocytes can induce functional T cell responses, including cytokine production and cytotoxicity.
• These findings suggest a significant role for keratinocytes in cutaneous immunity and potential applications in transcutaneous therapies.