Differentiation of Ly49s-positive or -negative natural killer cells is inhibited by anti-H-2b monoclonal antibodies acting at the level of bone marrow progenitors from B6 mice.

To investigate the role of MHC class I on in vitro differentiation of natural killer (NK) cells, a CD44low/-CD2-classlow population was isolated from mouse bone marrow. This population, which lacked expression of NK-1.1, Ly49A, Ly49C/I, and Ly49G, generated populations of NK-1.1+ NK cells expressing Ly49A, Ly49C/I, or Ly49G when cocultured for 13 days with syngeneic supportive stromal cells in the presence of interleukin 2. Ly49A and Ly49C/I were absent on the progeny of progenitors tested after 7 days of culture but were expressed as a late event together with low-level expression of NK-1.1, from day 8 of culture. The addition of anti-H-2b monoclonal antibody to cultures at day 0 inhibited proliferation of progenitors supported by either syngeneic, allogeneic, or H-2b-deficient stromal cells, thus suggesting that the effect was not exerted on stromal cells. Additional analyses demonstrated that class Ilow progenitors generated class I+ cells on which the anti-H-2b monoclonal antibody exerted its inhibitory effect.

Effect of neoadjuvant chemotherapy on Ki67 labelling index, c-erbB-2 expression and steroid hormone receptor status in human breast tumours.

The administration of neoadjuvant chemotherapy to breast cancer (BC) patients with operable disease allowed studies aimed of exploring the interaction between cytotoxic treatment and tumour biology in vivo. 99 patients with T2-4, NO-1, M0 primary BC received a median of 3 cycles of either CMF regimen (cyclophosphamide, methotrexate, 5-fluorouracil) or single agent epirubicin. Endocrine therapy was also concomitantly administered in the first 45 patients with estrogen receptor positive (ER+) BC. 92 ended the treatment plan. Ki67 labelling index, estrogen receptor (ER), progesterone receptor (PgR), and c-erbB-2 oncoprotein expression were evaluated immunohistochemically in tumour biopsies obtained before and after chemotherapy. At post-chemotherapy evaluation, tumour shrinkage greater than 50% was obtained in 71 patients (79.7%), 27 of them being complete responders (30.3%). The median Ki67 labelling index, which was 13% in the first biopsy, decreased to 4.5% (p < 0.001) upon mastectomy. No significant differences were observed in steroid hormone receptor and c-erbB-2 expression before and after neoadjuvant treatment. In conclusion, neoadjuvant chemotherapy, whether associated or not to endocrine therapy, leads to a significant decrease in BC proliferation without any appreciable impact on c-erbB-2 and steroid hormone receptor expression.