We examined the expression of S1PR1 mRNA and expression of the receptor’s transcriptional regulator, Krüppel-Like Factor 2 (KLF2), in thymocytes by real-time quantitative RT-PCR and examined thymic S1PR1 by flow cytometry in the context of HIV infection, which we have previously characterized in non-infected thymocytes [12]. Here, S1PR1 is linked to HIV infectious disease.