LpMab-19 Recognizes Sialylated O-Glycan on Thr76 of Human Podoplanin

Human podoplanin (hPDPN) is expressed in lymphatic vessels, pulmonary type-I alveolar cells, and renal glomerulus. The hPDPN/C-type lectin-like receptor-2 (CLEC-2) interaction is involved in platelet aggregation and cancer metastasis. High expression of hPDPN in cancer cells or cancer-associated fibroblasts (CAFs) leads to a poor prognosis for cancer patients. In our previous research, we reported on several anti-hPDPN monoclonal antibodies (mAbs), including LpMab-2, LpMab-3, LpMab-7, LpMab-9, LpMab-12, LpMab-13, and LpMab-17 of mouse IgG₁ subclass, which were produced using CasMab technology. Here we produced a novel anti-hPDPN mAb LpMab-19 of mouse IgG_2b subclass. Flow cytometry revealed that the epitope of LpMab-19 includes O-glycan, which is attached to Thr76 of hPDPN. We further identified the minimum epitope of LpMab-19 as Thr76-Arg79 of hPDPN. Immunohistochemistry revealed that LpMab-19 is useful for detecting not only normal cells, including lymphatic vessels, but also glioblastoma and oral squamous cell carcinoma cells. LpMab-19 could be useful for investigating the physiological function of O-glycosylated hPDPN.