External quality control study of lymphocyte subset tests in Japan.

We have evaluated external quality assurance of lymphocytes subset tests in Japan. The data suggest: 1) Values of lymphocyte subsets were variable at each medical laboratory in Japan. 2) Value of CD3 did not varied so much, but that of CD 19/20 or NK marker was widely varied. 3) Values of CD4 and CD8 varied in small extension. 4) CV of values was relatively low when analysis was carried out in commercial laboratories or when antibodies and instrument of Ortho-Clinical Diagnostics were used. 5) In some cases, CV was also relatively low if number of cell washing times was low or if self made lytic agents were used for cell lysing.