Infected malnourished children displayed changes in early activation and lymphocyte subpopulations.

Aim: Malnutrition and infections cause immunological changes in lymphocyte subpopulations and their functionality. We evaluated the activation capacity of lymphocytes and memory cells in 10 well nourished, seven well-nourished infected and eight malnourished infected children before and after treatment.

Methods: All the children were patients in Mexico City and were less than three years of age. The expression of various cluster of differentiation (CD) cells was assessed by flow cytometry: CD45RA (naïve) and CD45RO (memory) antigens on CD4 lymphocytes and CD69 in all lymphocytes.

Results: Well-nourished infected children showed a higher percentage of activated T lymphocyte (T cells), CD8+ and CD4+ memory cells during the infectious phase, suggesting that the activation mechanisms were triggered by infection. T cells from malnourished infected children showed a lower percentage of activated and memory cells. The T cell population size returned to baseline during the resolution phase of the infection in well-nourished infected children, but their T, B lymphocyte and natural killer (NK) cell counts remained high. In malnourished infected children, activated NK cells counts were low before and after therapy.

Conclusion: After therapy, malnourished infected children showed poor NK cell responses during the infection's resolution phase, suggesting a persistent malnutrition-mediated immunological deficiency.