Human Parvovirus B19 May Be a Risk Factor in Myasthenia Gravis with Thymoma

Area of Science:

• Immunology
• Virology
• Pathology

Background:

• Myasthenia gravis (MG) pathogenesis is complex, with thymic abnormalities implicated.
• Human parvovirus B19 (B19V) has been previously associated with thymic hyperplasia-related MG.
• Further investigation is needed to clarify the role of B19V in thymoma-associated MG.

Purpose of the Study:

• To investigate the relationship between B19V and thymoma-associated myasthenia gravis (MG).
• To assess the prevalence of B19V DNA and VP2 protein in thymomas.
• To correlate B19V presence with clinicopathological features, including germinal centers (GCs) and MG.

Main Methods:

• Analysis of 708 thymoma cases.
• Detection of B19V DNA using nested and quantitative PCR.
• Immunohistochemistry and fluorescent multiplex immunohistochemistry for B19V VP2 protein.
• Electron microscopy for viral particle visualization.
• Correlation with clinicopathological data, including MG and GCs.

Main Results:

• Patients with MG or ectopic GCs were significantly younger.
• Ectopic GCs were more frequent in thymomas associated with MG.
• B19V DNA positivity correlated significantly with the presence of GCs.
• B19V VP2 protein was detected in neoplastic thymic epithelial cells and GCs.
• B19V particles were observed in TECs and B cells within GCs.

Conclusions:

• The pathogenesis of MG is strongly linked to the presence of ectopic GCs in thymomas.
• B19V infection is a plausible contributor to the formation of ectopic GCs in thymoma.
• This study provides novel insights into the etiopathogenic mechanisms of B19V in thymoma-associated MG.