Cytotoxicity of leukocytes from normal and Shigella-susceptible (opium-treated) guinea pigs against virulent Shigella sonnei.

Intraepithelial lymphocytes were collected from the ileum of adult Hartley strain guinea pigs and used as effector cells in a 60-min bactericidal assay with virulent Shigella sonnei as target cells. Natural killer cytotoxicity (NKC) and antibody-dependent cellular cytotoxicity (ADCC) were measured and correlated with the resistance of the animals to infection by S. sonnei. Normal guinea pig intraepithelial lymphocytes exhibited mean NKC and ADCC values of 22.8 +/- 5.0 and 34.1 +/- 13.6, respectively. These animals were resistant to oral challenge with virulent S. sonnei. Intraepithelial lymphocytes from guinea pigs which were fasted for 4 days demonstrated NKC and ADCC values similar to those of normal animals (31.0 +/- 8.1 and 41.7 +/- 6.7, respectively). These animals also were resistant to oral challenge. Intraepithelial lymphocytes from guinea pigs which were given 1 ml of deodorized tincture of opium 2 h before cell collection demonstrated deficient NKC (4.7 +/- 4.2) and ADCC (5.3 +/- 4.9) values but remained resistant to infection by S. sonnei. When guinea pigs were fasted for 4 days and given opium, deficient NKC (2.0 +/- 2.0) and ADCC (1.3 +/- 1.3) values were demonstrated; this group of animals was susceptible to infection by S. sonnei (P less than 0.04). These experiments demonstrated that opium treatment depresses one form of gut immunity. When combined with starvation, opium treatment may increase susceptibility to infection by shigellae by modulation of immunity in addition to the effects on gut motility and bacterial flora.