Development of anti-TPO antibodies and association with thrombocytopenia, neutropenia, and anemia.

Shown is the development of anti-TPO antibodies in the patient in relation to administration of PEG-rHuMGDF (shaded boxes) with chemotherapy (arrows) and G-CSF. Inhibitory antibody to TPO was not detected by RIA or bioassay on 6 occasions (minus signs). Inhibitory antibody to TPO was detected by RIA on 5 occasions (plus signs) and also by bioassay on 4 of these. The first sample positive on RIA was negative on bioassay. In the 4 samples positive on bioassay, inhibitory antibody to TPO was detected at serum dilutions of 1:200, 1:100, 1:100, and 1:100. (A) Platelet count, platelet transfusion requirements, and serum TPO levels (asterisks). (B) ANC. (C) Hemoglobin levels and red blood cell transfusion requirements.