Design of a phase 1 study of plerixafor treatment in adults with WHIM syndrome. Patients receiving G-CSF had the drug discontinued at the indicated time. Arrows indicate time of subcutaneous administration of plerixafor at the indicated dose. Vertical hash marks denote times of blood sampling for complete blood counts. Not shown: a sham saline injection of the same volume as the lowest drug dose was given on day −1 and the greatest drug dose on day +7.