IMMUNOCYTOCHEMICAL ANALYSIS OF TUMOR-CELLS IN PRE-CULTURE AND POST-CULTURE PERIPHERAL-BLOOD PROGENITOR-CELL COLLECTIONS FROM BREAST-CANCER PATIENTS

We examined peripheral blood progenitor cell (PBPC) collections and CD 34(+)-selected fractions cultured in PIXY321, a fusion protein compris ing analog interleukin-3 (IL-3) and granulocyte-macrophage colony-stim ulating factor (GM-CSF) domains, for the presence of contaminating tum or cells from 14 patients with advanced-stage breast cancer. Five of t he 14 (36%) pre-culture PBPC specimens contained immunocytochemically (ICC)-detectable tumor cells using two different cocktails of monoclon al antibodies (mAbs). After 10 days in culture with PIXY321, the CD34( +)-selected fractions showed a median 23.6-fold expansion of hematopoi etic cells. No ICC-positive tumor cells were detected in any post-cult ure specimens. We conclude that in vitro expansion of CD34(+)-selected PBPCs with PIXY321 can expand hematopoietic eel populations apparentl y without risk of expanding contaminating breast cancer cell populatio ns.