Effects of moderate and severe malnutrition in rats on splenic T lymphocyte subsets and activation assessed by flow cytometry

Abstract

Malnutrition is distributed widely throughout the world and is a particular problem in developing countries. Laboratory animals have been very useful in studying the effects of varying levels of malnutrition because non-nutritional factors that affect humans may be controlled. The objective of the present study was to determine the effects of moderate and severe malnutrition on lymphocyte proportions and activation markers of T cells in experimentally malnourished rats during lactation by flow cytometry. Lower absolute (total) and relative (%) numbers of CD3+ and CD4+ lymphocyte subpopulations were observed in moderately (second degree) and severely (third degree) malnourished rats compared with well-nourished rats (P < 0.05). Both groups of malnourished rats showed a significant decrease in the percentage of CD71+ cells at 24 h post-activation with phytohaemagglutinin (PHA). After 24 h activation of spleen cells with PHA, a lower percentage of CD25+ cells was observed in malnourished than well-nourished rats (P < 0.05). In conclusion, the results of this study indicated an altered expression of CD71 and CD25 during activation of T lymphocytes in malnourished rats and may partially explain increased susceptibility to infection associated with malnutrition. Moreover, these results demonstrated that moderate malnutrition affects the response of T lymphocytes as much as severe malnutrition.

Fig. 1

(a) The lymphocytes gate set in forward-scatter–side-scatter (SSC) distribution. (b) Fluorescein isothiocyanate (FITC)-SSC distribution; this gate was set on to restrict analysis to CD3⁺ cells. For analysis of activation markers the cells were selected by windows (a) and (b). (c, d) Examples of CD25 expression in unstimulated and stimulated cultures of splenocytes respectively.

Fig. 2

Mean percentages of T lymphocytes in activated and non-activated spleen cells of well-nourished (WN), moderately (MN2nd) and severely (MN3rd) malnourished rats. Values are means ± standard error. Statistical differences: *WN without phytohaemagglutinin (PHA) (−PHA) versus WN with PHA (+PHA), P < 0·05.

Fig. 3

Mean percentages of activated T lymphocytes of well-nourished (WN), moderately (MN2nd) and severely (MN3rd) malnourished rats. (a) CD3+ CD71⁺ lymphocytes. Significant difference (P < 0·05): basal: WN > MN3rd; −phytohaemagglutinin (PHA): WN > MN2nd; WN > MN3rd; +PHA: WN > MN2nd; WN > MN3rd. The percentages of spleen cells expressing the CD71 marker increased significantly in all three groups following in vitro cell activation with PHA. (b) CD3⁺CD25⁺ lymphocytes. There was no difference between basal and −PHA groups. The percentages of CD3⁺ CD25⁺ increased significantly in WN rats following in vitro spleen cell activation with PHA.