Michelutti A

The expression of the multidrug resistance-associated glycoprotein in B-cell chronic lymphocytic leukaemia

Summary. The expression of the multidrug resistance (MDR)‐associated 170 kDa glycoprotein (p170) was investigated in 63 cases of B‐cell chronic lymphocytic leukaemia (CLL), with two monoclonal antibodies (MRK‐16 and C‐219). By immunocytochemistry with MRK‐16 (63 cases), the great majority of the cells was positive, with a weak reaction in 61% of cases and a strong reaction in 39% of cases. By flow cytometry, the proportion of positive cells was 39±25% with MRK–16 (63 cases), and 23±22% with C–219 (36 cases). The expression of pl70 in leukaemic B‐lymphocytes suggests that also in B‐CLL the development of MDR can have some therapeutic relevance. By either method the proportion of positive cells was not related to prior treatment, time from diagnosis, absolute lymphocyte count, and clinical stage (Rais and workshop classifications), but 12 patients who were under treatment with α‐interferon had more positive cells than the other ones.