Peripheral blood lymphocyte subsets in infants with diarrhea with and without giardia lamblia infection

The aim of the present study was to define the cellular immune response during gastrointestinal Giar-dia lamblia infection in young children. The level of lymphocyte subsets was determined in the peripheral blood of infants with G. lamblia-associated diarrhea or acute gastroenteritis and from control infants without diarrhea. The proportion of peripheral blood lymphocytes (PBL) expressing the CD8 marker (suppressor cytotoxic T cells) and the CD57 marker (natural killer cells and subset of CD8+ T cells) was highest in infants with acute gastroen­teritis, lower in infants without diarrhea, and lowest among those with G. lamblia -associated diarrhea. The level of CD4+ PBL (helper T cells) did not differ significantly among the three groups of children tested. The level of memory, or helper-inducer, CD4+CD29+ PBL was in­creased markedly in acute gastroenteritis as compared with their level among the other two groups, whereas naive or virgin CD4+CD45RA+ PBL had the reciprocal distribu­tion among the three groups of infants. In contrast to acute gastroenteritis from other causes, G. lamblia -associated diarrhea did not elicit changes in lymphocyte subsets.