FIG. 5.

Proliferative and Ca²⁺ responses in splenic B cells from Ntal^−/− mice and Lat^−/− Ntal^−/− double-deficient mice. (A) Spleen B cells purified from wild-type (WT) or Ntal^−/− mice were stimulated with increasing concentration of goat F(ab)′₂ anti-mouse IgM antibody (0-40 μg/ml), with lipopolysaccharide (1 μg/ml), or with phorbol myristate acetate and ionomycin (P/I). After 40 h of culture, the ATP content of each culture, a value proportional to the extent of cell proliferation, was measured by luminescence. (B) Calcium flux analysis in response to BCR stimulation in wild-type and Ntal^−/− mature B cells. The diagram depicts calcium flux (y axis) as a function of time (x axis). Arrow below the x axis indicates the time point of stimulation with F(ab)′₂ goat anti-mouse IgM antibody. Data shown are representative of four independent experiments. (C) Intra- and extracellular Ca2⁺ mobilization was recorded (see Materials and Methods) in mature B cells from wild-type (WT) or Ntal^−/− spleens. Same symbols as in panel B. The time point at which the extracellular Ca2⁺ concentration was restored to 1.3 mM is indicated by an arrow. (D) Calcium flux analysis in response to BCR stimulation in wild-type and Ntal^−/− B220⁺ IgD⁻, immature B cells. Same symbols as in panel B. (E) Calcium flux analysis in response to BCR stimulation in wild-type, Ntal^−/−, and Lat^−/− Ntal^−/− mature B cells. Same symbols as in panel B. (D) Calcium flux analysis in response to BCR stimulation in wild-type and Lat^−/− mature B cells. Same symbols as in panel B.