Identification of Homing Receptors and Activation-Linked Surface Antigens on Human Mast Cells and Basophils

Mast cells (MC) and basophils (BA) are key effector cells in atopic disorders. Development, homing, and activation of these cells are regulated by various surface antigens. We examined the expression and cytokine-mediated regulation of functionally relevant surface antigens on human BA and MC. Primary BA were obtained from healthy or allergic donors, or patients with chronic myeloid leukemia (CML). Primary MC were isolated from lung, skin, normal/reactive bone marrow (BM) or BM of patients with mastocytosis. The BA cell line KU812 and the MC lines HMC-1, ROSA, and MCPV-1 were also examined. As assessed by flow cytometry, BA expressed CXCR4, PD-L1, LMIR1, CLEC10A, LAIR1, EMR2, JAM-1, Siglec-6, Siglec-7, Frizzled-4, EVI-2B, CLEC4A, and CLEC12A. FGFR3 was detected on CML BA and interleukin-3-activated BA, but not on normal resting BA. Moreover, interleukin-3 augmented the expression of aminopeptidase-N, dipeptidyl-peptidase-4, ICAM-1, VEGFR3, and NKp30, and decreased CXCR4 expression on BA. Lung-, skin-, and BM MC exhibited Nectin-2, Siglec-1, CXCR4, PD-L1, LAIR1, EMR2, JAM-1, Siglec-6, CLEC12A, MRGPRX2, and Siglec-8. The KIT-ligand stem cell factor was found to promote expression of PD-L1 and TIM-3 on MC whereas interferon-gamma augmented only PD-L1 expression. Together, MC and BA exhibit unique profiles of activation-linked surface molecules, including cytokine-inducible checkpoint-antigens.