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Expression of monocyte activation antigen Mo3 on the surface of peripheral blood monocytes from patients with
P Dore-Duffy1, C Donovan, R F Todd
1Department of Neurology, Wayne State University School of Medicine, Detroit, MI 48201.
Abstract:
Exposure of human peripheral blood monocytes (PBM) to phorbol esters, bacterial products, and cyclic adenosine monophosphate agonists is known to stimulate expression of a plasma membrane antigen ([Ag]; Mo3). Mo3 is recognized by two monoclonal antibodies, Mo3e (IgM), and Mo3f (IgG). Surface Mo3 is barely detectable by indirect immunofluorescence flow cytometry in nonstimulated monocytes. Mo3-positive monocytes have been found in inflammatory tissues, but increased surface expression of Mo3 in PBM has not been seen in any patient group. We report that PBM from patients with chronic progressive MS (CPMS) express increased Mo3. PBM from patients with other neurologic diseases and healthy controls express little measurable Mo3. No difference was seen in class II major histocompatibility complex Ag expression and in Mo2 (CD14) expression. Exposure of PBM to lipopolysaccharide (10 mg/ml) enhanced Mo3 expression in both MS patients and controls. Mo3 expression on CPMS PBM was not dependent on culture conditions. Taken together, our observations suggest that monocytes from patients with MS are stimulated in vivo to express activation Ag Mo3, but that Mo3-positive monocytes need not be upregulated for HLA-DR.
Insights
Peripheral blood monocytes (PBM) from patients with chronic progressive multiple sclerosis (CPMS) show increased surface expression of the Mo3 activation antigen. This suggests in vivo monocyte activation in CPMS, independent of HLA-DR expression.
Area of Science:
- Immunology
- Neuroimmunology
Background:
- Monocytes express plasma membrane antigens (Ag) like Mo3 upon stimulation.
- Mo3 is typically undetectable on nonstimulated monocytes but found in inflammatory tissues.
- Previous studies have not identified increased Mo3 expression in peripheral blood monocytes (PBM) in any patient group.
Purpose of the Study:
- To investigate Mo3 expression on PBM in patients with chronic progressive multiple sclerosis (CPMS).
- To determine if PBM from CPMS patients exhibit increased Mo3 surface expression compared to controls.
Main Methods:
- Indirect immunofluorescence flow cytometry was used to detect Mo3 expression on PBM.
- Comparison of Mo3 expression in PBM from CPMS patients, other neurologic disease patients, and healthy controls.
- Assessment of class II major histocompatibility complex Ag and Mo2 (CD14) expression.
Main Results:
- PBM from CPMS patients exhibited significantly increased Mo3 surface expression.
- PBM from patients with other neurologic diseases and healthy controls showed minimal Mo3 expression.
- Lipopolysaccharide stimulation enhanced Mo3 expression in both MS patients and controls, indicating preserved responsiveness.
Conclusions:
- Monocytes from CPMS patients are activated in vivo, leading to increased Mo3 expression.
- Elevated Mo3 expression on PBM may serve as a biomarker for monocyte activation in CPMS.
- Mo3-positive monocytes are not necessarily upregulated in conjunction with HLA-DR in CPMS.