Time and temperature stability of T-cell subsets evaluated by a dual-platform method.

INTRODUCTION

T-cell subset enumeration in HIV patients is routinely performed for monitoring infection stage and response to antiretroviral therapy. Studies have examined the effect of specimen refrigeration and age for single-platform (SP) methods, but there is limited data for time and temperature requirements of dual-platform (DP) methods.

METHODS

Using a DP method, we analyzed peripheral blood (PB) from 52 HIV patients at room temperature (RT) at 24, 72, and 96 hours. PBs from 34 HIV patients had baseline RT analysis within 24 hours, and then were refrigerated and analyzed at 24, 48, and 72 hours. The coefficient of variation (CV) and residuals (changes in lymphocyte subsets) were recorded at each time point and compared to assess the precision and bias under the various conditions. Testing performance under different conditions was compared by linear regression.

RESULTS

Mean CV was ≤7.3% and median residuals were <30/μl for absolute CD4 and CD8 determinations. There was good correlation between baseline analysis data at RT and at various time points, both at RT and 4°C.

CONCLUSIONS

Our results are similar to those published for SP methods for aging or refrigerated specimens. The high level of agreement between measurements supports the robustness of this DP methodology.