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Expression of MHC class I determinants on erythrocytes of SLE patients
C M Giles1, M J Walport, J David
1Department of Immunology, Royal Postgraduate Medical School, Hammersmith Hospital, London, UK.
Insights
Increased expression of Major Histocompatibility Complex (MHC) Class I on erythrocytes is linked to Systemic Lupus Erythematosus (SLE) disease activity. This finding suggests aberrant immune antigen expression in autoimmune diseases.
Area of Science:
- Immunology
- Hematology
- Autoimmune Diseases
Background:
- Systemic Lupus Erythematosus (SLE) is an autoimmune disease characterized by immune system dysregulation.
- Major Histocompatibility Complex (MHC) antigens play a crucial role in immune responses.
- Previous observations noted MHC Class I on erythrocytes in C4-deficient SLE patients.
Purpose of the Study:
- To investigate the expression of MHC Class I on erythrocytes in SLE patients.
- To determine the correlation between erythrocyte MHC Class I expression and SLE disease activity.
- To explore the potential induction of MHC Class I on erythrocytes in autoimmune conditions.
Main Methods:
- Haemagglutination assays using human cytotoxic antisera and monoclonal antibodies.
- Detection of polymorphic HLA determinants (HLA-A, -B, -C) and beta 2-microglobulin.
- Comparison of erythrocyte MHC Class I expression in SLE patients, Rheumatoid Arthritis (RA) patients, and healthy controls.
Main Results:
- Strong MHC Class I expression was observed on erythrocytes of C4-deficient SLE patients.
- 30 out of 35 non-C4 deficient SLE patients showed markedly increased erythrocyte MHC Class I expression.
- A positive correlation was found between erythrocyte MHC Class I expression and SLE disease activity.
- Moderate and low expression were noted in RA patients and normal controls, respectively.
- MHC Class II antigens were not detected on erythrocytes.
Conclusions:
- MHC Class I may be induced on erythrocytes during SLE, potentially due to mediators from activated immune cells.
- Aberrant MHC antigen expression in tissues might be more prevalent in immune-mediated diseases than previously thought.
- This study highlights a potential biomarker for SLE activity and suggests broader implications for understanding immune mechanisms in disease.
Abstract:
Strong expression of MHC Class I determinants had been observed on the erythrocytes of three genetically C4 deficient patients who all had SLE. In a study of 35 other SLE patients who were not C4 deficient, 30 showed a marked increase in the expression of MHC Class I on their erythrocytes. There was a correlation between the expression of erythrocyte Class I and disease activity. The polymorphic HLA determinants were detected by haemagglutination with human cytotoxic antisera from untransfused pregnant women. A shared monomorphic epitope of HLA-A, -B and -C, and beta 2-microglobulin were detected by haemagglutination with monoclonal antibodies. A monoclonal antibody for a monomorphic epitope on MHC Class II alpha and beta chains did not react. Erythrocytes from a group of RA patients and a group of normal controls had moderate and low expression respectively. We suggest that MHC Class I may be induced on erythrocytes maturing in a milieu containing mediators derived from activated cells of the immune system. Aberrant tissue expression of MHC antigens may be more widespread than has been previously recognized in diseases mediated by immune mechanisms.