[Frontiers in Bioscience E2, 928-939, June 1, 2010]

Lymphocytes prime activation is required for nicotine-induced calcium waves

Landais Emilie1, Liautaud-Roger Françoise1, Antonicelli Frank2

1Secteur Prevention, Jean-Godinot Institute, 1 Avenue du General Koenig, 51056 Reims Cedex, 2University of Reims Champagne-Ardenne, Biochemistry Laboratory, CNRS UMR-6237, UFR Medicine, 51095 REIMS Cedex, France

TABLE OF CONTENTS

1. Abstract
2. Introduction
3. Material and methods
3.1. Reagents
3.2. Cell culture
3.3. Calcium influx assay
3.4. RNA isolation, Reverse Transcriptase RT-PCR
3.5. Immunostaining
4. Results
4.1. Nicotine induces calcium influx in PHA-stimulated lymphocyte
4.2. Stimulation of PBL by PHA modulates nicotinic receptor expression
4.3. Calcium influx and expression of nicotinic receptors by various leukemic cell lines
4.4. Expression of the α7 nicotinic receptor protein by leukemic cell lines and human PBL
4.5. Nicotine stimulates calcium influx through activation of the α7 subunit in stimulated PBL
5. Discussion
6. Acknowledgments
7. References

1. ABSTRACT

Lymphocytes are reported to express nicotinic acetylcholine receptors (nAChR). However, no data are available on the expression of these nAChR on activated lymphocyte relatively to resting lymphocytes. In this study, we examined nAChR subunits expression in PHA-stimulated versus un-stimulated lymphocytes, and four leukemic cell lines. Cell stimulation with nicotine triggered calcium responses only in some experiments conducted with PHA-stimulated lymphocytes. Likewise, only the Jurkat and HL-60 cell lines displayed calcium waves upon nicotine stimulation, whereas the Raji and CCRF-CEM did not. All responding cells displayed an active form of the nicotinic α-7 nAChR. Indeed, use of 2 different sets of primers for the corresponding mRNA showed that expression of the full-length α-7 subunit mRNA was only present in PHA-stimulated lymphocytes for which calcium waves had been evidenced. Microscopy analysis of lymphocytes structure showed a direct relationship between their size, their α-7 nAChR expression, and calcium release upon nicotine stimulation. Then, this relationship suggested that lymphocytes need a prime activation to express the α-7 nAChR, and therefore to release calcium in response to nicotine.