Aberrant glycosylation of mucins on the surface of adenocarcinomas lea
ds to exposure of novel tumor-associated epitopes potentially recogniz
able by the immune system. Monoclonal antibodies (mAbs) have been deve
loped against some of these epitopes, One such mAb, denoted CC49, reco
gnizes the tumor-associated glycoprotein TAG-72, Most adenocarcinomas,
including breast, colon, ovarian, prostate, and gastric, express some
form of this molecule, recognizable by the CC49 antibody. The widespr
ead distribution of the antigen on transformed cells makes the CC49 mA
b a potentially powerful tool in numerous immunotherapy contexts, In t
he course of our studies with CC49 and certain of its molecularly engi
neered derivatives, we screened a number of human hematopoietic cell l
ines for TAG-72 expression by flow cytometry using CC49, We found that
the T-cell line, Jurkat, had a higher level of CC49 mAb binding than
any of the carcinoma cell lines previously evaluated in our laboratory
. In addition, the myelomonocytic cell line Tf-1 and the erythroleukem
ia cell line K562 were also positive for CC49 mAb binding by flowcytom
etric analysis, However; peripheral blood lymphocytes and certain othe
r hematopoietic cell lines were not able to bind the CC49 mAb, Immunob
lot analyses of cell extracts from the CC49 reactive lines indicated d
istinct protein species reactive with the CC49 antibody. In some insta
nces, cells expressing these reactive proteins were susceptible to ant
ibody-dependent cellular cytotoxicity using a chimeric derivative of t
he CC49 antibody. These results indicate that the cell membrane expres
sion of molecules recognized by CC49 extends beyond adenocarcinomas to
certain cell lines of hematopoietic origin.