Analysis of peripheral blood dendritic cell subtypes in thymomatous MG

The object of this work was to measure the levels of monocyte-derived dendritic cell precursors (pDC1) and plasmacytoid dendritic cell precursors (pDC2) in peripheral blood mononuclear cells (PBMC) of patients with thymomatous MG and to assess the ratio of pDC1/pDC2 in these patients. Three-colour monoclonal antibody labelling technology was used to detect the cell counts and ratio of pDC1 and pDC2 in PBMCs of 18 patients with myasthenia gravis (MG), nine thymomatous patients without MG, and 15 normal controls. The number of pDC and pDC subsets in peripheral blood of patients with thymomatous generalized MG was significantly lower than that in thymomatous controls before and after the treatment. After the treatment, patients with both generalized MG and ocular MG had significantly lower number of pDC compared with thymomatous controls. We found no significant differences in pDC1/pDC2 ratio among groups. Before the extended thymomatous treatment, the number of pDC in patients with generalized MG was significantly lower than that in patients with ocular MG (P < 0.05). The counts of peripheral blood pDC and pDC subsets of patients with thymomatous MG were significantly lower 1 week after extended thymectomy. The counts of pDC and pDC subsets decreased in generalized thymomatous MG, and the patients with generalized MG had lower pDC counts than the patients with ocular MG before the treatment. Treatment resulted in decreased counts of pDC and pDC subsets in thymomatous MG. We suggest that the level of peripheral blood pDC can be used as a marker to define the progress of the disease.