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Conventional rapid latex agglutination in estimation of von Willebrand factor: method revisited and potential clinical applications.

Mahat M, Abdullah WZ, Hussin CM - J Immunol Res (2014)

Bottom Line: Measurement of von Willebrand factor antigen (VWF : Ag) levels is usually performed in a specialised laboratory which limits its application in routine clinical practice.So far, no commercial rapid test kit is available for VWF : Ag estimation.The latex agglutination test can be performed qualitatively and semiquantitatively.

View Article: PubMed Central - PubMed

Affiliation: Departments of Haematology, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, 16150 Kubang Kerian, Kelantan, Malaysia.

ABSTRACT
Measurement of von Willebrand factor antigen (VWF : Ag) levels is usually performed in a specialised laboratory which limits its application in routine clinical practice. So far, no commercial rapid test kit is available for VWF : Ag estimation. This paper discusses the technical aspect of latex agglutination method which was established to suit the purpose of estimating von Willebrand factor (VWF) levels in the plasma sample. The latex agglutination test can be performed qualitatively and semiquantitatively. Reproducibility, stability, linearity, limit of detection, interference, and method comparison studies were conducted to evaluate the performance of this test. Semiquantitative latex agglutination test was strongly correlated with the reference immunoturbidimetric assay (Spearman's rho = 0.946, P < 0.001, n = 132). A substantial agreement (κ = 0.77) was found between qualitative latex agglutination test and the reference assay. Using the scoring system for the rapid latex test, no agglutination is with 0% VWF : Ag (control negative), 1+ reaction is equivalent to <20% VWF : Ag, and 4+ reaction indicates >150% VWF : Ag (when comparing with immunoturbidimetric assay). The findings from evaluation studies suggest that latex agglutination method is suitable to be used as a rapid test kit for the estimation of VWF : Ag levels in various clinical conditions associated with high levels and low levels of VWF : Ag.

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Positive (number 5) and negative (number 6) reactions of qualitative latex agglutination test for VWF : Ag.
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Related In: Results  -  Collection


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fig1: Positive (number 5) and negative (number 6) reactions of qualitative latex agglutination test for VWF : Ag.

Mentions: The detection and estimation of VWF by latex agglutination test can be performed using a qualitative test and semiquantitative test, respectively. Qualitative test was performed on undiluted plasma sample, and the result was reported as negative or positive. Invisible or hardly visible agglutination was reported as negative and visible agglutination was reported as positive (Figure 1). For a positive result, the degree of agglutination was scored from 1+ to 4+ based on the size of the agglutinated beads, the appearance of the background, and the rapidity of the agglutination development as shown in Table 1. Semiquantitative test was performed on diluted plasma sample. A positive plasma sample was serially diluted twofold with normal saline. The highest dilution that still shows a positive reaction is the end-titre of a sample.


Conventional rapid latex agglutination in estimation of von Willebrand factor: method revisited and potential clinical applications.

Mahat M, Abdullah WZ, Hussin CM - J Immunol Res (2014)

Positive (number 5) and negative (number 6) reactions of qualitative latex agglutination test for VWF : Ag.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4352515&req=5

fig1: Positive (number 5) and negative (number 6) reactions of qualitative latex agglutination test for VWF : Ag.
Mentions: The detection and estimation of VWF by latex agglutination test can be performed using a qualitative test and semiquantitative test, respectively. Qualitative test was performed on undiluted plasma sample, and the result was reported as negative or positive. Invisible or hardly visible agglutination was reported as negative and visible agglutination was reported as positive (Figure 1). For a positive result, the degree of agglutination was scored from 1+ to 4+ based on the size of the agglutinated beads, the appearance of the background, and the rapidity of the agglutination development as shown in Table 1. Semiquantitative test was performed on diluted plasma sample. A positive plasma sample was serially diluted twofold with normal saline. The highest dilution that still shows a positive reaction is the end-titre of a sample.

Bottom Line: Measurement of von Willebrand factor antigen (VWF : Ag) levels is usually performed in a specialised laboratory which limits its application in routine clinical practice.So far, no commercial rapid test kit is available for VWF : Ag estimation.The latex agglutination test can be performed qualitatively and semiquantitatively.

View Article: PubMed Central - PubMed

Affiliation: Departments of Haematology, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, 16150 Kubang Kerian, Kelantan, Malaysia.

ABSTRACT
Measurement of von Willebrand factor antigen (VWF : Ag) levels is usually performed in a specialised laboratory which limits its application in routine clinical practice. So far, no commercial rapid test kit is available for VWF : Ag estimation. This paper discusses the technical aspect of latex agglutination method which was established to suit the purpose of estimating von Willebrand factor (VWF) levels in the plasma sample. The latex agglutination test can be performed qualitatively and semiquantitatively. Reproducibility, stability, linearity, limit of detection, interference, and method comparison studies were conducted to evaluate the performance of this test. Semiquantitative latex agglutination test was strongly correlated with the reference immunoturbidimetric assay (Spearman's rho = 0.946, P < 0.001, n = 132). A substantial agreement (κ = 0.77) was found between qualitative latex agglutination test and the reference assay. Using the scoring system for the rapid latex test, no agglutination is with 0% VWF : Ag (control negative), 1+ reaction is equivalent to <20% VWF : Ag, and 4+ reaction indicates >150% VWF : Ag (when comparing with immunoturbidimetric assay). The findings from evaluation studies suggest that latex agglutination method is suitable to be used as a rapid test kit for the estimation of VWF : Ag levels in various clinical conditions associated with high levels and low levels of VWF : Ag.

Show MeSH