The expression of activating natural killer cell receptors in patients with primary breast cancer.

Abstract

Abstract Abstract #5047 Background: The effect of primary breast tumours and their subsequent treatment on immune system function is still poorly understood and may have critical implications with regard to disease recurrence and success of treatment with the new generation of biologicals. In line with our interest in the expression and role of natural killer (NK) cell activating receptors, we measured the expression of NK cell surface receptors NKp30, NKp46 and NKG2D in patients with primary breast cancer. NKp30 and NKp46 are members of the natural cytotoxic receptors (NCRs) and are expressed on the majority of NK cells of healthy individuals. NKG2D is a member of the C type lectin superfamily. These receptors activate NK cells upon stimulation and are involved in NK cell tumour recognition and triggering although their ligands on tumour cells remain elusive.
 Methods: Our experimental procedure involved obtaining serial blood samples prior to and post surgery (4 hours-6 months) in patients with primary breast cancer. This allowed us to study basal levels of NK cell receptors as well as to investigate the effect of surgery and post surgery treatment on receptor expression. NK receptor analysis was performed on whole blood by three colour flow cytometry using antibodies against CD3, CD56 and the NK receptors with samples analysed on a FACSCalibur flow cytometer (BD).The data was analysed using CELLQuest.
 Results and Discussion: NK cells were defined as CD3-, CD56+ lymphocytes and their frequency, as measured by the three colour staining protocol, was broadly in agreement with the levels found using four colour antibody staining and Trucount tubes (BD). The majority of patients expressed NKp30, NKp46 and NKG2D at levels consistent with that seen in age and sex matched control samples obtained from healthy individuals. However, in a number of patients (10/30), the levels of NKp30 and NKp46 expression were low at all timepoints tested. The levels of NKp30 were generally lower than NKp46 and were unrelated to surgery. NKG2D expression was less affected with the levels similar to that found in controls individuals. The significance of these findings with respect to NK cell target recognition is unclear as an array of activating and inhibitory receptors are involved in NK cell activation and target recognition. This staining approach has also allowed us to assess the relative frequency of CD56dim and CD56bright NK cells. In healthy individuals the majority of NK cells are CD56dim whilst around 5% are CD56bright. These are considered to represent a functionally distinct population. In a number of patients in this study, the expression of CD56 on NK cells was relatively low with the consequential decrease in the frequency of CD56bright cells. We are prospectively following the importance of these NK cell differences with respect to patient health, and disease free and overall survival. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5047.