Immunologic cross-reactivity between different albumin-bound isocyanates.

Area of Science:

• Immunology
• Occupational Health

Background:

• Isocyanate exposure can lead to IgE-mediated sensitization.
• Understanding cross-reactivity is crucial for diagnosing and managing isocyanate sensitization.

Purpose of the Study:

• To evaluate immunologic cross-reactivities among different isocyanate-protein conjugates in sensitized workers.
• To investigate the nature of antigenic determinants in isocyanate sensitization.

Main Methods:

• Radioallergosorbent test (RAST) and skin testing were performed on sera from six isocyanate-sensitized workers.
• RAST inhibition assays were used to assess cross-reactivities between various isocyanate-human serum albumin (HSA) conjugates.
• Ovalbumin-bound toluene diisocyanate (TDI) was tested to evaluate carrier specificity.

Main Results:

• All sera showed IgE antibodies reacting with isocyanates workers were exposed to and others they were not.
• Moderate to strong cross-reactivities were observed between different isocyanate-HSA conjugates, including aromatic and aliphatic types.
• Individual variations in cross-reactivity magnitudes and specificities were noted, with one serum showing high specificity to TDI-HSA.
• Isocyanate-HSA conjugates demonstrated carrier-specific antigenicity, with determinants likely formed by the isocyanate-protein bond and adjacent residues.

Conclusions:

• Isocyanate-protein conjugates share closely related antigenic determinants, leading to cross-reactivity.
• Individual differences in antibody specificity and avidity influence the immune response to isocyanates.
• The isocyanate-protein bond and surrounding amino acids are key in forming the specific antigenic determinants.