Interlaboratory variability in multiplexed pneumococcal antibody testing  David C. LaFon, MD, Moon H. Nahm, MD  Journal of Allergy and Clinical Immunology  Volume 143, Issue 3, Pages 1255-1257 (March 2019) DOI: 10.1016/j.jaci.2018.10.057 Copyright © 2018 American Academy of Allergy, Asthma & Immunology Terms and Conditions

Fig 1 Interlaboratory correlation results for serotypes 4 (A), 20 (B), and 23F (C). X-axis values represent pneumococcal IgG antibody levels (μg/mL) for laboratory A, with Y-axis values representing antibody levels from laboratory B (open circle) or C (solid circle). Boxes show correlation coefficients (r) for each interlaboratory comparison. There was strong correlation (r ≥ 0.70) across all 3 comparisons for only 1 serotype (serotype 4, Fig 1, A). There was weak correlation (r ≤ 0.50) for all 3 comparisons for 4 serotypes (including serotype 20, Fig 1, B). There was strong correlation between A and C, with weaker correlation for other comparisons for 8 serotypes (including serotype 23F, Fig 1, C). Journal of Allergy and Clinical Immunology 2019 143, 1255-1257DOI: (10.1016/j.jaci.2018.10.057) Copyright © 2018 American Academy of Allergy, Asthma & Immunology Terms and Conditions

Fig 2 Protective vs nonprotective classification of pneumococcal IgG levels by different laboratories. Individual measurements were categorized as nonprotective or protective on the basis of the specified thresholds, and are represented by red and green shaded boxes, respectively. Numbered rows represent serum samples, with columns representing serotypes. An asterisk to the right of a sample's row indicates overall “protected” status for that sample (at least 70% of serotypes at or above the protective threshold). Empty boxes indicate 3 missing measurements from laboratory B (serotype 1 from 2 samples, and 15B from another), which was unable to analyze these serotypes because of a nonlinear dilution response for those samples. A, Classification of pneumococcal IgG levels based on AAAAI criteria. A threshold of 1.3 μg/mL was used to categorize individual measurements as nonprotective (<1.3 μg/mL, red shaded boxes) or protective (≥1.3 μg/mL, green shaded boxes). B, Classification of pneumococcal IgG levels based on the World Health Organization recommendations for pneumococcal vaccine evaluation. A threshold of 0.35 μg/mL was used to categorize individual measurements as nonprotective (<0.35 μg/mL, red shaded boxes) or protective (≥0.35 μg/mL, green shaded boxes). Journal of Allergy and Clinical Immunology 2019 143, 1255-1257DOI: (10.1016/j.jaci.2018.10.057) Copyright © 2018 American Academy of Allergy, Asthma & Immunology Terms and Conditions