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Major histocompatibility complex class II antigen expression in nerves in leprosy; an immunoelectronmicroscopical
S A Cowley1, S E Gschmeissner, Y Negesse
1Department of Pathology, Royal College of Surgeons of England, London.
Summary
Major histocompatibility class II expression in leprosy nerves was investigated. Schwann cells in leprosy nerves did not express class II molecules, suggesting they may not present Mycobacterium leprae antigens in vivo.
Area of Science:
- Immunology
- Neuroscience
- Pathology
Background:
- Major histocompatibility complex (MHC) class II molecules are crucial for antigen presentation to T cells.
- Schwann cells are the primary glial cells of the peripheral nervous system.
- Leprosy is a chronic infectious disease caused by Mycobacterium leprae, primarily affecting nerves.
Purpose of the Study:
- To investigate the expression of MHC class II molecules in leprosy nerves.
- To determine the role of Schwann cells in antigen presentation in leprosy.
Main Methods:
- Immunoelectron microscopy was employed to examine nerve biopsies from leprosy patients.
- Expression of MHC class II molecules was assessed on various nerve cell types.
Main Results:
- In normal nerves, endothelial cells and occasional endoneural cells showed constitutive MHC class II expression.
- In leprosy nerve biopsies (both paucibacillary and multibacillary), infiltrating leukocytes were MHC class II positive.
- Notably, Schwann cells in leprosy nerves did not exhibit MHC class II positivity.
Conclusions:
- Schwann cells may not be involved in presenting Mycobacterium leprae antigens to T cells in the context of leprosy.
- The in vivo environment of Schwann cells, including basement membranes and axonal association, might inhibit MHC class II expression or antigen presentation.
- These findings contrast with in vitro studies and highlight the importance of the in vivo microenvironment in immune cell function.