Modulation of [Ca2+](i) in freshly isolated mouse lymphocytes with in vivopriming

Studied at the level of the individual cell, the pattern of [Ca2+](i) mobil ization of in vivo sensitized mouse lymphocytes by T-dependent antigen (KLH ), challenged in vitro by Con A, PHA or anti-CD3 epsilon mAb in different p eriods after immunization, was as follows. In the entire DLN lymphocyte pop ulation and in tested T cell subsets from immunized mice, baseline [Ca2+](i ) was significantly increased and cells were able to respond additionally t o stimuli. In KLH-primed DLN lymphocytes, calcium mobilization in response to membrane receptor-dependent stimuli (anti-CD3 epsilon, PHA, and ConA) wa s increased. Enhancement of Ca2+ mobilization is parallel with changed immu nophenotype. These findings suggested that: (a) [Ca2+](i) mobilization coul d correlate with lymphocyte behaviour during immunization and that mobiliza tion 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 gamma delta TCR+ cells; (c) the quantitative measurement of [Ca2+](i) could be an important biochemical parameter to st udy cellular-reaction to a specific antigen. (C) 1999 Elsevier Science B.V. All rights reserved.