CD33 and systemic mastocytosis: Notably, (CD4loCSF1R-CD33-CD14+), (CD33-HLA-DMA-CD14+), (CSF1R+CD86-CD14+) and (CXCL8+CSF1R-IL1B-CD14+) classical monocytes decreased significantly in the SM patients (Table 1), suggesting that these cell subsets may negatively associated with the disease symptoms.