Dasatinib (BMS-354825) is a Src/ABL tyrosine kinase inhibitor currently approved 
for the treatment of chronic myeloid leukemia. Dasatinib has increased potency 
against ABL compared to the current therapy imatinib, and is effective in many 
cases where disease is resistant to imatinib. Dasatinib also inhibits many 
Src-family tyrosine kinases. We have demonstrated in this study that dasatinib 
is able to block the function of normal human T-lymphocytes in vitro at 
clinically relevant concentrations. T-cell functions including proliferation, 
activation and cytokine production were all uniformly inhibited in the presence 
of dasatinib. We also demonstrated inhibition of TCR signalling through 
Src-family kinase LCK, and predicted that inhibition of LCK and other kinases 
involved in T-cell signalling by dasatinib is responsible for the suppression of 
T-cell function. These findings raise the concern about potential T-cell 
inhibition in patients taking dasatinib, and suggest a possible application for 
the treatment of T-cell mediated immune disorders.