Abstract.Platelets are crucial components of the tumor microenvironment that function to promote tumor progression and metastasis. In the circulation, the interaction between tumor cells and platelets increases invasiveness, protects tumor cells from shear stress and immune surveillance, and facilitates tumor cell extravasation to distant sites. However, the role and presence of platelets in the primary tumor have not been fully determined. Here, we investigated the presence of platelets around breast cancer primary tumor cells and the associations between these cells. We further investigated the associations among platelets, tumor cells, chemoresistance, and epithelial-mesenchymal transition (EMT). We retrospectively analyzed data from 74 patients with human epidermal growth factor receptor 2 (HER2)-negative breast cancer who underwent biopsies before treatment and subsequent neo-adjuvant chemotherapy. In biopsy specimens, we evaluated the expression of platelet-specific markers and EMT markers using immunohistochemistry. The associations among the expression of platelet-specific markers in biopsy specimens, EMT, response to neo-adjuvant chemotherapy, and survival were analyzed. The presence of platelets was observed in 44 out of 74 (59%) primary breast cancer biopsy specimens. Platelet-positive tumor cells showed EMT-like morphological changes and EMT marker expression. Primary tumor cells associated with platelets were less responsive to neo-adjuvant chemotherapy (pCR rate: 10 vs. 50%, respectively; p=0.0001). Platelets were an independent predictor of the response to chemotherapy upon multivariable analysis (p<0.0001). In conclusion, there was a significant association between platelets surrounding primary tumor cells in the biopsy specimens and the chemotherapeutic response in breast cancer. Platelets surrounding primary tumor cells may represent novel predictors of chemotherapeutic responses.

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A virus has been isolated from the tissues of a pigeon with visceral lesions that were characterized by focal necrosis of parenchymatous tissue, by the presence in affected cells of intranuclear inclusions of the herpetic type, and by secondary inflammatory reaction. This newly recognized virus, which has been tentatively called the I.N.I. agent is pathogenic for pigeons and embryonated eggs but is avirulent for rabbits, guinea pigs, and mice. The virus is smaller than the agent of psittacosis and is immunologically different from it. The I.N.I. agent and psittacosis virus were both of etiological importance in an epizootic among pigeons. Some birds were infected simultaneously with the two agents while others were infected with only one.

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