We previously demonstrated that Ca signals in T-cells from human lamina propria (LP-T) are decreased compared to Ca signals from peripheral blood T-cells (PB-T). In lymphocytes from inflamed intestine, a large increase in Ca signals and a concomitant increase in cell proliferation were observed (JBC 279, 5641-5647 (2004), EJI 34, 3477-3484 (2004)). We report that a similar reduction of Ca signals in LP-T cells compared to PB-T cells was not found in mice. Following Ca store depletion, Ca influx through CRAC channels was indistinguishable between PB and LP-T cells. Another difference between human and mouse intestine was the relative number of T-cells (CD3⁺) versus B-cells (CD19⁺). Whereas we found twice as many T-cells than B-cells in human colon, we had on average eight times more B-cells than T-cells in the murine colon preparation. The magnitude of Ca influx was comparable between PB-B cells and LP-B cells from mouse intestine. This is again different from human intestine, in which Ca signals in LP-B cells were significantly smaller than the ones in PB-B cells. The important question now is whether or not Ca signals are increased in lymphocytes from inflamed mouse intestine. To address this, we induced an experimental colitis in mice through a seven day application of dextran sulphate sodium (DSS). Establishment of colitis was confirmed by rectal bleeding. Preliminary results indicate that Ca signals are similar in B-cells from DSS and control mice.