T-cell enumeration from dried blood spots by quantifying rearranged T-cell receptor-beta genes

Significant hurdles remain to large-scale implementation of medical interventions in the developing world due to the lack of a modern diagnostic infrastructure. This is especially pertinent to the international roll-out of antiretroviral drugs to treat HIV, which ideally includes a CD4 T-cell count to determine eligibility. We designed a novel technique to estimate mature T-cell numbers by calculating the amount of rearranged T-cell receptor beta genes from dried blood spots of HIV-infected individuals in the United States and Uganda. It was observed that the rearranged T-cell receptor beta count correlated well with total lymphocyte counts from both study populations (Baltimore R=0.602, Uganda R=0.497; p<0.001) and the ability for this measurement to determine antiretroviral initiation was similar to total lymphocyte counts, which can be used to determine eligibility in HIV+children. This technique as well as other dried blood spot based technologies could increase the diagnostic and monitoring capabilities in resource-limited settings.