Down-regulation of Qa-2 after intravenous injection of siRNA into BD mice. A. BD mice were injected once with control siRNA or Qa-2 siRNA (500 nmol/mouse), which was composed of the α3 domain, transmembrane domain, and cytoplasmic domain. PBMC collected from the orbital sinus before and 1 day after injection were analyzed by flow cytometry. Qa-2 siRNA effectively reduced the Qa-2 levels in the PBMC of BD mice. B. Two days after injection, the frequency of Qa-2 positive lymphocytes and granulocytes was analyzed in Qa-2 siRNA injected BD mice. In lymphocytes and granulocytes, Qa-2 siRNA significantly reduced the number of Qa-2 positive cells when compared to glucose-injected control mice. C. The frequency of Qa-2 positive cells in mice that were injected with Qa-2 siRNA four times. Specifically, 500 nmol control siRNA or Qa-2 siRNA in 200 μl of 5% glucose solution was intraperitoneally injected four times with a three day interval between injections, and the PBMC were analyzed by FACS two days after the last injection. In lymphocytes and granulocytes, Qa-2 siRNA significantly reduced the Qa-2 positive cells when compared to glucose injected control mice.