The relationship between mucosal immunoresponse and clinical outcome in patients with recurrent upper respiratory tract infections treated with a mechanical bacterial lysate.

This open prospective study aims to evaluate whether a therapy with a polyvalent mechanical bacterial lysate (PMBL) could be associated to the enhancement of the locoregional immunoresponse in patients with recurrent upper respiratory tract infections. Forty patients (23 females and 17 males) were enrolled, 33 of whom concluded the study. The duration of the study was six months and each patient was visited five times. Twenty-six patients had an objective improvement in clinical and medical locoregional conditions, while in seven patients the treatment did not result in an objective amelioration. Twenty-five out of 27 patients with clinical response were characterized by an increase of specific antibodies against PMBL antigens in salivary fluids. Only two patients, with a non-significant clinical result, had a slight increase in the concentration of salivary specific IgA. The association between PMBLspecific immunoglobulin titers and clinical results was significant for IgG and IgA, but not significant for IgM. Th1 switch was detected only in patients with clinical amelioration, while the Th0 phenotype was observed in three responder and four non-responder patients. Weak Th2 polarization was also observed in one clinical responsive patient. The capacity of effectively opsonizing living bacteria was detected in samples derived from responder patients. These results suggest that PMBL treatment was able to trigger an efficient and well-targeted immune-response resulting in positive clinical outcome of the patients treated.