Attenuation of influenza-like symptomatology and improvement of cell-mediated immunity with long-term N-acetylcysteine treatment

Eur Respir J 1997; 10: 1535–1541 DOI: 10.1183/09031936.97.10071535 Printed in UK - all rights reserved

Copyright ERS Journals Ltd 1997 European Respiratory Journal ISSN 0903 - 1936

Attenuation of influenza-like symptomatology and improvement of cell-mediated immunity with long-term N-acetylcysteine treatment

S. De Flora*, C. Grassi**, L. Carati+

Attenuation of influenza-like symptomatology and improvement of cell-mediated immu- nity with long-term N-acetylcysteine treatment. S. De Flora, C. Grassi, L. Carati. ©ERS Journal Ltd 1997.
ABSTRACT: N-acetylcysteine (NAC), an analogue and precursor of reduced glu- tathione, has been in clinical use for more than 30 yrs as a mucolytic drug. It has also been proposed for and/or used in the therapy and/or prevention of several respiratory diseases and of diseases involving an oxidative stress, in general. The objective of the present study was to evaluate the effect of long-term treatment with NAC on influenza and influenza-like episodes.

A total of 262 subjects of both sexes (78% 65 yrs, and 62% suffering from non- respiratory chronic degenerative diseases) were enrolled in a randomized, double- blind trial involving 20 Italian Centres. They were randomized to receive either placebo or NAC tablets (600 mg) twice daily for 6 months. Patients suffering from chronic respiratory diseases were not eligible, to avoid possible confounding by an effect of NAC on respiratory symptoms.

NAC treatment was well tolerated and resulted in a significant decrease in the frequency of influenza-like episodes, severity, and length of time confined to bed. Both local and systemic symptoms were sharply and significantly reduced in the NAC group. Frequency of seroconversion towards A/H1N1 Singapore 6/86 influenza virus was similar in the two groups, but only 25% of virus-infected subjects under NAC treatment developed a symptomatic form, versus 79% in the placebo group. Evaluation of cell-mediated immunity showed a progressive, significant shift from anergy to normoergy following NAC treatment.

Administration of N-acetylcysteine during the winter, thus, appears to provide a significant attenuation of influenza and influenza-like episodes, especially in elder- ly high-risk individuals. N-acetylcysteine did not prevent A/H1N1 virus influenza infection but significantly reduced the incidence of clinically apparent disease. Eur Respir J 1997; 10: 1535–1541.