Diisocyanate Antigen-stimulated Monocyte Chemoattractant Protein-1 Synthesis Has Greater Test Efficiency than Specific Antibodies for Identification of Diisocyanate Asthma

We previously reported that diisocyanate-human serum albumin (DIISO-HSA) stimulated production of monocyte chemoattractant protein-1 (MCP-1) by peripheral blood mononuclear cells is significantly associated with a clinical diagnosis of diisocyanate asthma (DA). Others have reported that antibodies for DIISO-HSA are specific but insensitive markers of DA. This study was performed to evaluate test characteristics of the in vitro MCP-1 assay compared with DIISO-HSA-specific immunoglobulin (Ig) G and IgE in identifying workers with DA. MCP-1 was quantitated in peripheral blood mononuclear cell supernatants 48 hours after incubation with DIISO-HSA antigens. Assay results were compared with outcomes of specific inhalation challenge (SIC) testing. Nineteen of 54 (35%) workers assayed for antibodies and MCP-1 stimulation had SIC-confirmed DA. Mean MCP-1 produced by SIC-positive workers was greater than SIC-negative workers (p < or = 0.001). Diagnostic sensitivity, specificity, and test efficiency for specific IgG were 47%, 74%, and 65%, respectively, and for specific IgE were 21%, 89%, and 65%, respectively. Sensitivity, specificity, and test efficiency of the MCP-1 test were 79%, 91%, and 87%, respectively. This study indicates that the MCP-1 stimulation assay has greater sensitivity and specificity than the specific antibody assays in correctly identifying DA.