Control lymphocyte subsets: Can one country's values serve for another's?

Reliable interpretation of abnormal immunity depends on an understanding of what constitutes “normal.” We and others have reported that lymphocyte patterns are affected by ethnicity, sex, and environmental factors.1-3 Differing exposure to infectious agents, such as malaria, tuberculosis, and cytomegalovirus, could underlie differences in lymphocyte subset patterns in contrasting settings.4-6 In this study we analyzed combined data from 3 studies of healthy children from Thailand,1 Malawi,2 and the United States 3 who had used similar standard flow cytometric methods and markers, thus allowing assessment of immune heterogeneity across settings with differences in ethnicity and infectious disease exposure.