CAMPATH-1G is an IgG2b rat antihuman (CDw52) monoclonal antibody (MoAb
) which is currently being used for T cell depletion in the setting of
allogeneic bone marrow transplantation (BMT). In addition it elicits
substantial lymphoid depletion, an effect which is being explored for
remission induction in patients with lymphoid malignancies and for tre
ating patients with various autoimmune disorders, in particular rheuma
toid arthritis. Recently, in vivo CAMPATH-1G has been introduced to ac
hieve increased immunosuppression in the pretransplant conditioning, f
or prevention of graft rejection following T cell depleted BMT. Here w
e describe a patient with T cell Lymphoblastic lymphoma who received i
n vivo CAMPATH-1G as part of the pretransplant conditioning regimen an
d who, 6 days after the first dose, developed severe migratory polyart
hritis. This is the first report of severe migratory polyarthritis as
a very unusual complication following CAMPATH-1G MoAb administration.