Characterisation and evaluation of external quality assessment scheme serum. Discussion paper from the European External Quality Assessment (EQA) Organisers Working Group C

This work reviews the procurement, specification and manufacture of serum for external quality assessment (EQA) and provides a checklist for scheme organisers. Guidance on the assessment of commutability and notes on the use of EQA materials to assess assay problems are provided. The importance of the appropriateness of materials in respect of scheme design and objectives, and the essential nature of a detailed specification prior to manufacture are emphasised.

Assessment of biological reagents for presence of human immunodeficiency virus-1 (HIV-1) antigens

We tested 122 biological reagents including laboratory quality assurance sera and therapeutic human immune serum globulin products using an immunoenzymometric assay (IEMA) for HIV-1 antigens. Biological reagents tested were 64 HIV-1 antibody non-reactive and 44 HIV-1 antibody reactive quality assurance samples, and 14 HIV-1 antibody reactive human immune serum globulins from 21 manufacturers. Twenty-one of these biological reagents were previously reported by us as Western blot reactive. All 122 samples tested were non-reactive for HIV-1 antigens. Low incidence of HIV-1 antigen in these biological reagents should not alter laboratory safety practices in which all samples are considered infectious. Use of HIV-1 antigen measurements, either alone or with HIV-1 antibody determinations does not increase the likelihood of detecting HIV-1 reactive samples.

Sensitivity and specificity of pooled versus individual sera in a human immunodeficiency virus antibody prevalence study

We evaluated the efficacy of testing pooled versus individual sera for the detection of human immunodeficiency virus antibody. A total of 5,000 individual specimens and 500 pools of 10 specimens each were assayed by an enzyme-linked immunosorbent assay. There was complete agreement in human immunodeficiency virus enzyme-linked immunosorbent assay reactivity for pooled versus individual specimens. An estimated savings of 60 to 80% (labor and supplies) can be realized dependent upon pooling and assay format.

Presence of antibodies to human immunodeficiency virus-1 in reference reagents of human origin in diagnostic kits

We tested 54 reagents of human origin that were included in a number of diagnostic kits to be used as positive or negative control material, and for quality assurance, for the presence of antibodies to human immunodeficiency virus-1 (HIV-1). Of these, 12 (22%) reagents were found to give positive results for antibodies to HIV-1 by enzyme-linked immunosorbent assay and/or supplementary tests. These results suggest that some diagnostic reagents of human origin may be contaminated with HIV-1 and potentially may be infectious.