Aim: 1. Characterize the Euclidean distance ratio in patients with Bw4 and Bw6 reactivity. 2. Determine if PCA analysis and Euclidean distance ratios can identify antibody verified eplet patterns of reactivity in the single antigen bead assay.
Methods: Renal, lung, or cardiac transplant patients with Bw4 only reactivity (N=5), Bw4 with additional reactivity (N=7), Bw6 reactivity (N=4), or no specific Bw4/Bw6 reactivity (N=20), comprising 319 samples for solid phase class I single antigen bead testing, were analyzed using principal component analysis (PCA). The Euclidean distance ratio (EDR) was calculated for each patient. Bw4 and Bw6 reactive pattern patients were compared to non-Bw4/Bw6 pattern patients. To evaluate PCA analysis in identifying different eplet patterns of reactivity, patients with patterns of antibody verified eplet reactivity for single antigen bead class I solid phase testing were assessed and EDRs were calculated. The EDRs for identified antibody confirmed eplet patterns were compared to EDRs for absent eplet patterns.
Results: Upon PCA analysis and comparing our patient cohorts, it was found that patient samples with both Bw4 and Bw6 had significantly higher Euclidean distance ratios (EDR)s and were visually distinct compared to our control group of patients which lacked specific Bw4 and Bw6 pattern reactivity. When using PCA to assess patients which exhibited distinct eplet patterns of reactivity, there was a visual separation of these beads involved in these patterns of reactivity from other panel beads. The calculated EDRs specific for the antibody verified eplet patterns was significantly higher when compared to other eplet patterns which were absent.
Conclusion: PCA is utilized by various computer learning algorithms, applications and software to identify variance and pattern differences in variables of interest. Our study using PCA analysis in analyzing patient solid phase single antigen bead test results suggests that PCA analysis would be a valuable tool to assisted detection of epitope and eplet patterns of reactivity in the results from single antigen bead class I solid phase testing.
