Measurements of the proinflammatory cytokines production by blood monocytes (MON) or PBMC from healthy elderly and young subjects. Peripheral blood was obtained from volunteers, and the cells were purified as described in the Material and Methods section. Monocytes and PBMC were challenged with LPS (100 ng/mL), or not (Basal), for 18 and 24 hours, respectively, and cytokine production was determined by ELISA. Columns represent the median and error bar the interquartile range. The results were evaluated by Mann–Whitney Rank Sum Test. In the same subject group, statistical differences are represented by continuous lines (cells stimulated or not) and letters for different cell types. Asterisks indicate statistical difference between groups of subjects (p values - *0,0487; a 0,0029; b 0,0068; c 0,0061; d 0,0195; e 0,0180; ** 0,0399; f 0,0089; g 0,0098).