MECHANISMS OF ADJUVANCY .1. METAL-OXIDES AS ADJUVANTS

The exact mechanism of how immune adjuvants function still remains lar gely unknown, despite their long history of use, This work reports the properties of alum and the related compounds Al(OH)(3) or Al2O3. Expe riments were performed in rats to determine the relative adjuvancy of silica, talc, ground glass, Al2O3, SnO2, ZrO2, hematite and magnetite, Antibody response and cell-mediated immunity (CMI) to ovalbumin (OVA) were determined and were found to be significantly enhanced by silica and talc, Antibody response to OVA was moderately enhanced by Al2O3 h ematite, and magnetite, while CMI to OVA was not affected, SnO2 ZrO2, and ground glass only gave a slight adjuvant effect, The magnitude of adjuvancy appeared to correlate with the magnitude of the inflammatory response produced by each metal oxide and also correlated with their surface area. No correlation could be drawn between the hydrophilicity or hydrophobicity of tile metal oxides and the magnitude of their adj uvancy. (C) 1997 Elsevier Science Ltd.