CD33 and lung carcinoma: Based on these surface markers, we found that while CD11b+CD33+HLA-DR− cells (MDSC) circulate in lung cancer patients at baseline (preoperation, T0), the frequency of CD11b+CD33+HLA-DR− cells was significantly increased on postoperative day 1, 3 and 7 (T1, T2 and T3, respectively) (Fig. 1a, b).