PMN–tumor cell conjugate formation.

PMNs were incubated with DiD-labeled neuroblastoma cells alone (control), GM-CSF alone, hu14.18 with or without GM-CSF, or hu14.18/GM-CSF immunocytokine for 30, 60, 90, and 120 minutes. (A) In this example, the expression of CD11b by PMNs is shown after 60 minutes with an FITC–anti-CD11b mAb, and data are presented as dual-color diagrams. (B) PMN–tumor cell conjugates were identified as CD11b⁺DiD⁺ events and are represented as the number per 10 000 events at the indicated times. Data are from 1 of 5 experiments that gave similar results.