Chronic cell-mediated immune reactions to metals

Area of Science:

• Immunology
• Toxicology
• Materials Science

Background:

• Cell-mediated immune reactions are suspected in toxic responses to metals like chromium (Cr), nickel (Ni), zirconium (Zr), beryllium (Be), and mercury (Hg).
• The mechanism of metal-protein interaction, specifically how metals act as haptens, remains unclear.
• Metal-induced antigenicity changes, potentially altering protein configuration, may explain cross-reactivity between metals such as Zr and Cr.

Purpose of the Study:

• To investigate the role of cell-mediated immunity in toxic metal reactions.
• To explore the hapten mechanism of metals in immune responses.
• To assess methods for inducing and preventing metal sensitivity.

Main Methods:

• Sensitization of guinea pigs to Be and Hg via epicutaneous contact.
• Induction of Cr, Ni, and Zr sensitivity using Freund's adjuvant and intradermal injections.
• Comparison of three protocols for metal sensitization efficacy.
• Induction of specific unresponsiveness to Cr and Ni via intratracheal installation before sensitization.
• Induction of unresponsiveness to Cr after sensitization using intravenous metal injection and epicutaneous application.
• Observation of flare-up reactions at old Cr sites following intravenous metal injection.

Main Results:

• Contact sensitivity is the predominant reaction, though granulomas can form with Be and Zr.
• Epicutaneous contact effectively sensitizes guinea pigs to Be and Hg.
• Cr, Ni, and Zr sensitization requires adjuvant and frequent injections.
• Intratracheal administration can prevent Cr and Ni sensitization.
• Post-sensitization unresponsiveness to Cr is achievable.
• Intravenous metal injection can trigger reactions at previous Cr exposure sites.

Conclusions:

• Cell-mediated immunity plays a significant role in toxic metal reactions.
• Understanding metal-hapten interactions is crucial for explaining cross-reactivity.
• Effective methods exist for inducing and preventing metal sensitivity, offering potential therapeutic strategies.