PTPRC and chronic obstructive pulmonary disease: However, the direct correlation between the number of circulating CD45+CD34+CD133+ cells and the number of CD45+ infiltrates in pulmonary vessels and the presence of CD133+ cells, an intrinsic marker of progenitor cells, observed in the vessel wall might infer that in COPD patients, circulating CD45+CD34+CD133+ cells are recruited in response to injury to the pulmonary vessel wall, causing a reduction in circulating PCs numbers.