Reference range for T lymphocytes populations in blood donors from two different regions in Brazil

Abstract

This study defined the normal variation range for different subsets of T-lymphocyte cells count in two different Brazilian regions. We analysed the T-lymphocytes subpopulations (CD3+, CD4+, CD8+) in blood donors of two Brazilian cities, located in North (Belem, capital state of Para, indian background) and Northeast (Salvador, capital state od Bahia, African background) regions of Brazil. Results were compared according to gender, stress level (sleep time lower than 8 hours/day), smoking, and alcohol intake. Lymphocytes subpopulations were measured by flow cytometry. Five hundred twenty-six blood donors from two Brazilians cities participated in the study: 450 samples from Bahia and 76 samples from Pará. Most (60%) were men, 59% reported alcohol intake, 12% were smokers, and 80% slept at least 8 h/day. Donors from Bahia presented with significantly higher counts for all parameters, compared with Para. Women had higher lymphocytes levels, in both states, but only CD4+ cells count was significantly higher than men's values. Smokers had higher CD4+ counts, but sleep time had effect on lymphocytes levels only for Para's donors (higher CD3+ and CD4+ counts). That state had also, a higher proportion of donors reporting sleep time <8 h/day. The values for CD3, CD4 and CD8+ cells count were significantly higher in blood donors from Bahia than among those from Pará. Female gender, alcohol intake, stress level, and smoking were associated with higher lymphocyte counts. The use of a single reference range for normal lymphocytes count is not appropriate for a country with such diversity, like Brazil is.

Determination of lymphocyte subset reference ranges in peripheral blood of healthy adults by a dual-platform flow cytometry method

“…Moreover, relative and absolute values for T CD4+ count were higher in females and these findings were consistent with previous studies [3,6,7,14,16,17,19,22,23]. Maini and colleagues suggested that hormonal differences between genders might explain this difference in T CD4+ counts [15].…”

“…In this study, gender comparison showed differences only for T CD8+ absolute count, for which female had higher values, similarly to those reported in adults in the northern rural region of Tanzania [16]. Comparing the results of this study (Table 1) with those by Torres et al [23] showed differences in T CD8+ reference ranges for healthy Brazilian people.…”

“…This can be explained by the fact that it evaluated two different states (Bahia and Pará) with distinct colonization (African descendents and native Amerindians, respectively). These differences can be justified by methodological differences and environmental factors [23]. Unlike results in this study, most of the results showed no difference in T CD3+ relative and absolute values between genders [4,9,11,14,20].…”

“…Maini and colleagues suggested that hormonal differences between genders might explain this difference in T CD4+ counts [15]. Comparing this study with another one conducted in Brazil [23] showed differences in T CD4+ absolute reference range.…”

“…This large difference was attributed to genetic factors, since subjects living in the same geographic region were expected to be exposed to the same type of antigens, thus minimizing this kind of influence. In Brazil, one study [23] has evaluated relative and absolute lymphocyte counts and reference ranges for healthy subjects. Therefore, the aim of the present study was to determine reference ranges of lymphocyte subsets in peripheral blood by a dual-platform flow cytometry method in healthy Brazilian adults.…”