Sera were obtained from two groups of patients. Group A included 7 patients
with low-grade non-Hodgkin's lymphoma treated with three or more cycles of
standard-dose chemotherapy and recombinant human granulocyte-colony stimu-
lating factor (rhG-CSF). The cytokine was administered to half the patients after
the ®rst chemotherapy cycle and to the other half after the second according to
a randomized design and then to all patients from the third chemotherapy cycle
on, until documented hemopoietic reconstitution. Group B included 3 patients
with high-grade non-Hodgkin's lymphoma, 1 patient with resistant Hodgkin's
disease, and 1 patient with multiple myeloma who received high-dose chemotherapy
and rhG-CSF. Anti-G-CSF antibodies were detected in the sera of 4
patients. Both immunoglobulin IgM and IgG antibodies were detected at low
levels in pretreatment sera from one group A patient. IgG antibody titers increased
markedly during the ®rst and second periods of G-CSF administration. IgG class
antibodies developed in 3 group B patients during the ®rst course of rhG-CSF administration.
Circulating anti-G-CSF antibodies did not seem to affect hematological recovery.
Low levels of anti-G-CSF antibodies were also detected in sera (15/135) from
different healthy adults and in sera (5/40) from umbilical cord blood. Saturable
antibody binding and competition enzyme-linked immunosorbent assay (ELISA) and
immunoblotting con®rmed antibody speci®city