Volume 3 Supplement 1

23rd Congress of the International Association for Breast Cancer Research

Open Access

Spontaneous apoptosis of circulating T-lymphocytes and its correlation to their prolactin receptor expression and prolactin plasma levels in patients with breast cancer

  • T Bauernhofer1,
  • U Friebe-Hoffmann1,
  • T Hoffmann1,
  • G Dworacki1,
  • B Vonderhaar1 and
  • TL Whiteside1
Breast Cancer Research20013(Suppl 1):A8

DOI: 10.1186/bcr408

Received: 10 May 2001

Published: 31 May 2001

We have previously shown that a higher percentage of circulating CD3+ T lymphocytes undergo spontaneous apoptosis in cancer patients as compared with normal controls. Prolactin (PRL) has been reported to inhibit apoptosis in various cell types, including a Nb2 rat lymphoma cell line. In addition, there is evidence that the human PRL-antagonist hPRL-G129R induces apoptosis in breast cancer cell lines. We investigated a possible relationship between prolactin receptor (PRL-R) expression and apoptosis of CD3+ T lymphocytes, as well as PRL plasma levels, in patients with breast cancer. Peripheral blood mononuclear cells of patients (n = 11) and sex-matched normal controls (n = 12) were stained with AnnexinV, anti-Fas mAb (CD95), mouse antihuman PRL-R mAb B6.2, anti-CD3 mAb and respective isotype control mAbs. Multicolor flow cytometry was used to compare expression of these markers on T cell. In patients, 37 ± 19% (median ± SD) of CD3+ cells bound AnnexinV, marking early apoptosis of T lymphocytes compared with 17 ± 10% in controls (P <0.004). Furthermore, 82 ± 15% of the CD3+ T cells were Fas+ in patients, compared with 51 ± 9% in controls (P <0.0001). All CD3+ T lymphocytes were positive for PRL-R expression in breast cancer patients, as well as in normal control individuals. The mean fluorescence intensity of PRL-R on T lymphocytes of breast cancer patients was 106-172 (median 119) compared with 87-176 (median 123), suggesting no difference in PRL-R expression on T lymphocytes in patients versus controls. PRL plasma levels were comparable in patients and normal controls (4.8 ± 3.4 ng/ml versus 9.8 ± 4.6 ng/ml). In concordance with these findings, PRL was not able to inhibit the onset of apoptosis of Jurkat cells, a thymic lymphoma cell line, incubated with Fas cross-linking CH-11 mAb. These results indicate that PRL/PRL-R might not be involved in modulating Fas/Fas ligand interactions, which are, in part, responsible for apoptosis of T lymphocytes, leading to excessive turnover of T cells in the circulation of patients with breast cancer.

Authors’ Affiliations

(1)
University of Pittsburgh Cancer Institute, Pittsburgh, Philadelphia; and National Cancer Institute, NHI

Copyright

© BioMed Central Ltd 2001

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