Zinc-induced suppression of inflammation in the respiratory tract, caused by infection with human rhinovirus and other irritants.

Free ionic zinc (Zn2+) in saliva shortens duration and severity of common cold (CC) symptoms. It is proposed that Zn2+ complexes with proteins of critical nerve endings and surface proteins of human rhinovirus (HRV) (a) interrupt nerve impulses and (b) block docking of HRV on intercellular adhesion molecule-1 (ICAM-1) on somatic cells, thereby interrupting HRV infection. Since leukocyte function associated antigen-1 (LFA-1) binds leukocytes to cells through ICAM-1, initiating inflammation, Zn2+ is expected to block LFA-1/ICAM-1 binding and thereby suppress inflammation. This could explain reduction of inflammation experienced by persons taking zinc gluconate/glycine (ZGG) lozenges for CC. Allergic rhinitis (AR) and CC share many common symptoms, and ZGG also mitigates AR symptoms. Focal irritation, increased ICAM-1 expression, and recruitment of leukocytes to epithelial foci are the common elements. Zinc ions may be an important anti-inflammatory factor because they can block docking of both HRV and LFA-1 with ICAM-1.