IP-10 responses in DBS compared to DPS.

<p>QFT-CMV test stimulated blood from 8 healthy individuals, 5 CMV responders, were used to compare IP-10 signals in DBS and DPS samples. Nil antigen and mitogen samples pooled (n = 24). <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0039228#pone-0039228-g004" target="_blank">Figure 4A</a>. Correlation analysis, (p<0.0001, Spearman); <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0039228#pone-0039228-g004" target="_blank">Figure 4B</a> Bland-Altman plot of the same data. Each sample is represented on the graph as the average of the two measurements against the difference. The limits of agreement are specified as the average difference (bias, −0.8 pg/ml) ±1.96 standard deviation of the difference, (71 pg/ml).</p

Correlation between IP-10 detected in plasma and DPS (A), and between IP-10 detected in plasma and INF-γ detected in plasma (B).

<p>A total of 25 healthy donors were compared. Nil, CMV-antigen and mitogen samples were pooled, rendering a total of 75 data-points per graph (Spearman).</p

Overview of the development and validation process.

<p>Overview of the development and validation process.</p

IP-10 responses in plasma and DPS.

<p>QFT-CMV responses from 26 healthy individuals (Control group 2) were divided into CMV-positive (n = 17) and CMV-negative (n = 9) based on the QFT-CMV cut off for IFN-γ suggested by the manufacturer (0.2 IU/ml).</p

Magnitude of IP-10 (A) and IFN-γ (B) responses to antigen and mitogen challenge determined in plasma and DPS samples.

<p>Optical density reading from 18 Quantiferon-TB positive donors were compared. Nil, antigen and mitogen samples were pooled, rendering a total of 54 data-points per graph. OD readings from plasma and DPS samples were plotted against the IP-10 or IFN-g concentration determined in the plasma sample corrected for the dilution factor. The optimal working range of the assay is OD 0–3, a steadily increasing regression line ensures high precision.</p

Agreement between IP-10 (A) and IFN-γ (B) detected in plasma and DPS samples.

<p>IP-10 and IFN-γ signals were detected in samples from 18 Quantiferon-TB positive donors; nil, antigen and mitogen samples were corrected for the dilution factor in plasma. Samples were pooled rendering a total of 54 data-points per graph. DPS concentrations were analyzed as ng/2 discs for IP-10 and IU/2 discs for IFN-γ signals (DPS) and log transformed to facilitate comparison between high (plasma) and low DPS. Each sample is represented on the graph as the average of the two measurements against the difference. The limits of agreement are specified as the average difference (bias) ±1.96 standard deviation of the difference.</p

QuantiFERON-TB® Gold In-tube results for all study participants and according to HIV status.

<p>QFT-IT: QuantiFERON-TB® Gold In-tube test.</p>*<p>p-value for difference between HIV-negative and HIV–positive patients.</p

Antigen dependent and mitogen induced absolute IFN-γ levels by QuantiFERON-TB® Gold In-tube test result in HIV-negative and HIV-positive patients respectively.

<p>Horisontal lines represent medians. Dotted lines represent the applied cut-off values as recommended by the manufacturer: 0.35 IU/ml for antigen (ESAT-6, CFP-10, TB7.7) dependent IFN-γ production and 0.50 IU/ml for mitogen (PHA) induced IFN-γ production respectively. The assay is not able to quantify values above 10 IU/ml why values above this limit were assigned the value 10 IU/ml. No significant differences in median levels between HIV-positive and HIV-negative were observed.</p

Association of risk factors with an indeterminate QuantiFERON-TB® Gold In-tube result.

<p>A total of 23 out of 161 patients (14%) had a QFT-IT indeterminate result. No differences were found in OR when comparing QFT-IT positive and negative patients. OR: Odds Ratio. CI: Confidence interval. BMI: Body Mass Index. Age of 33 years and lymphocyte count of 1640 cells/µl represents medians for all patients. 3+ AFB by sputum smear microscopy: More than 10 acid fast bacilli (AFB) per field.</p

Demographic and clinical characteristics of patients according to HIV status.

*<p>p-value for difference between HIV-negative and HIV–positive patients. IQR: Inter-quartile range.</p>†<p>Smear grade by sputum microscopy: 0 (no acid fast bacilli [AFB] on smear), 1–9 (exact number of AFB per 100 fields), 1+ (10–99 AFB per 100 fields), 2+ (1–10 AFB per field) and 3+ (more than 10 AFB per field).</p