Expression of Natural Killer Receptors in T Lymphocytes and NK Cells Post Stem Cell Transplantation
H Olteanu, P Hari, BC Schur, SH Kroft. Medical College of Wisconsin, Milwaukee, WI
Background: Limited information is available on the natural killer cell receptor (NKR) reconstitution in mononuclear cells after bone marrow transplantation (BMT). We studied the expression of NKRs on peripheral blood cytotoxic T lymphocytes and NK cells in patients who underwent an allogeneic BMT and compared these findings with results from a control cohort.
Design: Peripheral blood samples were collected from 20 normal adult volunteers and 15 allogeneic stem cell transplant patients. Mononuclear cells were prepared by whole blood lysis prior to flow cytometric analysis. Four-color flow cytometry was performed with antibodies against T and NK cell-associated antigens CD3, CD56, CD57 and the NKRs CD158a, CD158b, CD158e (also known as killer immunoglobulin-like receptors, KIR5) and CD94. Expression of NKRs was evaluated separately in CD56(+), CD57(+) and CD56/CD57 (double +) subsets of T and NK cells, and compared in the two cohorts by the Mann-Whitney test.
Results: The mean absolute white blood cell count in the control group was 6,940 X 106/L, with mean T lymphocyte and NK cell percentages of 23% and 2.2%, respectively. The corresponding values in the BMT group were 5,980 X 106/L, 14% and 3.4%. CD158a and CD94 expression was variable, whereas CD158b and CD158e were generally detected on distinct subpopulations. The percentage of control cells expressing CD158a was significantly higher than in the BMT group in all subsets studied: CD56(+) T cells (413.9% vs. 283.2%, meanSEM; p=0.02); CD57(+) T cells (443.0% vs. 293.5%, p=0.02); CD56/CD57 (double +) T cells (563.4% vs. 404.3%, p=0.02); CD56(+) NK cells (463.1% vs. 303.3%, p=0.001); CD56/CD57 (double +) NK cells (633.3% vs. 495.1%, p=0.05). CD158b and CD158e percentage and expression levels were similar in the control and BMT groups, with the exception of CD158b in CD56/CD57 (double +) NK cells (393.8% vs. 534.2%, p=0.03). Furthermore, the CD94 mean fluorescence intensity was significantly different in the CD57(+) T lymphocytes (12924 vs. 455.9, p=0.0002) when comparing the controls with the BMT cohort.
Conclusions: Our study shows that T lymphocytes and NK cells in transplanted patients show differences in their NKR profile when compared to that of normal individuals, especially in CD158a expression. These preliminary results suggest that the immune reconstitution following BMT modulates NKR and CD94 expression differently in T and NK cells.
Wednesday, March 11, 2009 1:00 PM
Poster Session VI # 234, Wednesday Afternoon