The present invention relates to a bi-specific antibody or antibody
fragment having at least one arm that is reactive against a targeted
tissue and at least one other arm that is reactive against a targetable
conjugate. The targetable conjugate encompasses a hapten to which
antibodies have been prepared. In preferred embodiments, the hapten is
histamine-succinyl-glycine (HSG). In more preferred embodiments, the at
least one arm comprises the CDR sequences of the HSG-binding 679
antibody. The targetable conjugate is attached to one or more therapeutic
and/or diagnostic agents. The invention provides constructs and methods
for producing the bispecific antibodies or antibody fragments, as well as
methods for using them and kits comprising them.