Dubravko Forčić

γδTCR+ intestinal intraepithelial lymphocytes (i-IEL) in reaction against intestinal nematode Trichinella spiralis

To assess the gamma delta TCR T cells in the control of the timing of the mucosal response to enteric parasitic infections, we used C57BL mice, orally infected with 200 viable T. spiralis larvae. The small intestine, spleens and Peyers patches (PP) were excised on 1, 4, 7, 14, 21 and 29 postinfection days (p.i.) for immunophenotyping and histological studies. Uninfected mice served as control. Characterization of isolated lymphocytes of C57BL control mice, confirmed that T cell immunophenotype differs in spleen, PP and i-IEL. Practically all i-IEL were CD3+ cells (83%). In addition, most of the i-IEL expressed Ly-2 (65%). Among the i-IEL, the level of gamma delta TCR+ cells was significantly higher (29%) than that found in spleen (3%) and PP (3%). The expression was high on CD3+ and Ly-2+ (26 and 21%, respectively) and low on L3T4+ i-IEL (< 1%). During T. spiralis infection alpha beta TCR+ CD3+, gamma delta TCR+ CD3+ and gamma delta TCR+ Ly-2+ i-IEL increased on day 4 and 7. However, infected mice displayed a reduction in i-IEL number from 14 to 29 p.i. day. At the same time the proportion of gamma delta TCR on spleen Ly-2+ and on PP CD3+ and Ly-2+ cells increased on 14 and 21 p.i. day. Adult worms were expelled from the gut by day 14. Thus, the kinetics of gamma delta TCR+ i-IEL, but not spleen and PP gamma delta TCR, corresponded to the kinetics of worm expulsion in C57BL mice. Most murine i-IEL of the gamma delta T cell lineage tend to be cytolytic when activated. We speculated that gamma delta T cells of i-IEL during the early stages of infection recognize and eliminate damaged epithelial cells generated by parasite antigens, simultaneously accelerating the worm expulsion.

Modulation of [Ca2+]i in freshly isolated mouse lymphocytes with in vivo priming

Studied at the level of the individual cell, the pattern of [Ca2+]i mobilization of in vivo sensitized mouse lymphocytes by T-dependent antigen (KLH), challenged in vitro by Con A, PHA or anti-CD3epsilon mAb in different periods after immunization, was as follows. In the entire DLN lymphocyte population and in tested T cell subsets from immunized mice, baseline [Ca2+]i was significantly increased and cells were able to respond additionally to stimuli. In KLH-primed DLN lymphocytes, calcium mobilization in response to membrane receptor-dependent stimuli (anti-CD3epsilon, PHA, and ConA) was increased. Enhancement of Ca2+ mobilization is parallel with changed immunophenotype. These findings suggested that: (a) [Ca2+]i mobilization could correlate with lymphocyte behaviour during immunization and that mobilization clearly depended on kinetics of immune reaction; (b) the higher level of activity among sensitized lymphocytes was due to the increased number of specific B-cells (Ia(k+)) and gammadeltaTCR+ cells; (c) the quantitative measurement of [Ca2+]i could be an important biochemical parameter to study cellular reaction to a specific antigen.