RECURRENT RESPIRATORY INFECTIONS AND IMMUNOSTIMULANTS

Key words: Recurrent respiratory infection, Immunomodulants, Immunostimulants, Toll-like receptors

As for pharmacological prevention of recurrent respiratory infections Cochrane Library has examined 579 controlled clinical trials against placebo. The substances tested are very different, ranging from thymus extracts and synthetic molecules acting on thymus functions, to non-specific immunomodulants, whose effectiveness is recognised, such as levamisole, to herbal substances and to homeopathy. The effect of all the substances (except for homeopathy) has been positive. The results show, in most of the cases, a yearly, bimestrial, biannual reduction ranging from 30% to 50% in the number of infections. The effect is usually limited to the period of treatment. The concordance of the results, the high number of patients studied and most of the multi-centric trials support the natural conclusions that these substances are effective. Therefore, considering the present knowledge, it seems legitimate to affirm that different immunostimulants have a positive effect on recurrent infections that are usually due to an early socialisation in an age in which the immune system is largely immature. The substantially similar effect of different substances can be acceptably explained saying that they alarm the toll-like receptors, which are sensitive and nonspecific stimulators of the primary immune system that recognize short molecular sequences such as fragments of bacterial, or viral, or vegetal or tissue DNA. The work reports a series of trials carried out in the ‘80s in the Paediatric Clinic in Trieste (Italy) and by family paediatricians, who are ACP (Associazione Culturale Pediatri) members. It also reports a series of reviews or meta-analyses, ending with that by Cochrane.