Alpha 7 nicotinic acetylcholine receptor modulates lymphocyte activation.
OBJECTIVE
Even though the presence of alpha7 nicotinic receptor (nAChR) in lymphocytes has been demonstrated, its functional role still remains elusive. The aim of our study was to characterize alpha7 nAChRs in human lymphocytes upon phytohemagglutinin (PHA) stimulation.


METHODS
Lymphocytes were activated with the mitogen PHA. alpha7 nAChRs were studied by reverse transcription-polymerase chain reaction (RT-PCR), real time PCR, flow cytometry and confocal laser scanning microscopy. The effects of nicotinic drugs on PHA-induced proliferation was evaluated by the [(3)H]-thymidine incorporation assay.


RESULTS
We show that the expression of functional alpha7 receptors increases after PHA stimulation. The activation of peripheral lymphocytes by PHA increases 2.2-fold the alpha7 subunit mRNA expression and 4-fold the binding of the antagonist alpha-bungarotoxin (alpha-BTX) with respect to non activated lymphocytes. By measuring the increase of intracellular calcium in response to nicotine we determine that alpha7 receptors in lymphocytes are functional. Nicotinic drugs differentially modulate T cell activation. While nicotine tends to inhibit proliferative responses, specific alpha7 antagonists, such as alpha-BTX and methyllycaconitine, enhance cell division.


CONCLUSIONS
This study reveals that the alpha7 receptor modulates lymphocyte activation and contributes to clarifying the role of the non neuronal cholinergic system in the immune response.
De Rosa
María José
MJ
Instituto de Investigaciones Bioquímicas de Bahía Blanca, UNS-CONICET, Camino La Carrindanga Km7, B8000FWB Bahía Blanca, Argentina.
Dionisio
Leonardo
L
Agriello
Evangelina
E
Bouzat
Cecilia
C
Esandi
María Del Carmen
Mdel C
D000157:Aconitine / Q000031:analogs & derivatives / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D007202:Indicators and Reagents; D008213:Lymphocyte Activation / Q000187:drug effects / Q000502:physiology*; D018613:Microscopy, Confocal; D018722:Nicotinic Agonists / Q000494:pharmacology; D018733:Nicotinic Antagonists / Q000494:pharmacology; D010835:Phytohemagglutinins / Q000494:pharmacology; D011978:Receptors, Nicotinic / Q000187:drug effects / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D013936:Thymidine / Q000378:metabolism; D064569:alpha7 Nicotinic Acetylcholine Receptor
C579167:Chrna7 protein, human; D007202:Indicators and Reagents; D018722:Nicotinic Agonists; D018733:Nicotinic Antagonists; D010835:Phytohemagglutinins; D011978:Receptors, Nicotinic; D064569:alpha7 Nicotinic Acetylcholine Receptor; C054634:methyllycaconitine; D002795:Choline O-Acetyltransferase; D002118:Calcium; D013936:Thymidine; D000157:Aconitine