Sample Collection in PPTs Affects HIV-Load Testing

Use of plasma preparation tubes (PPTs) for sample collection in patients with human immunodeficiency virus 1 (HIV-1) could affect the results of viral RNA load testing.

HIV-1 load is an important marker of disease progression and treatment efficacy in patients with HIV-1 infection. An increase in the number of samples with detectable HIV-1 RNA has been reported among patients with previously suppressed viral loads.

Scientists studied whether the overestimation of HIV-1 RNA was due to the presence of cells in plasma from plasma preparation tubes. Anne-Marte Bakken Kran and colleagues, at the department of microbiology, national reference laboratory for HIV, Oslo University Hospital (Ulleval, Norway), carried out the investigation. They demonstrated that HIV-1 RNA levels in plasma collected in PPTs that had been centrifuged before being transported to the laboratory were elevated compared with those collected in PPTs that had been centrifuged after arrival in the laboratory.

In addition, plasma from the PPTs that had been centrifuged before transport to the laboratory also contained cell-associated HIV-1 nucleic acids and abundant blood cells, a finding not observed with PPTs that were centrifuged after

The authors concluded that transportation of PPTs after centrifugation could cause release of cells in the plasma fraction containing cell-associated HIV-1 nucleic acids. These cells contributed significantly to the HIV-1 RNA copy numbers in patients with low viral loads.

The study was published in the July 2009 edition of the Journal of Clinical Microbiology.

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