Figure 9. MHC block and Ca²⁺transients in steady state lymph nodes.

(A) The frequency of cell-wide and local (sparkles) Ca²⁺ transients in CD-Salsa6f (Hom) lymph nodes 48 hr after injection of MHC class I and II blocking antibodies (MHC), isotype control antibody (ITC), or no antibody (Con). Red bars indicate mean values. For MHC-blocked compared to ITC, the relative event frequencies were: for cell-wide, 314 ± 38 vs 553 ± 77, mean ± SEM, p=0.06; for sparkles, 532 ± 44 vs 1343 ± 272, mean ± SEM, p=0.02, Mann-Whitney test. (B,C) Integrated green channel intensities of Ca²⁺ transients normalized to SD of green channel for cell-wide events (B) and for sparkles (C). Red bars indicate mean values. For MHC-blocked vs ITC, the relative amplitudes were: for cell-wide (B), 321 ± 14 vs 350 ± 15, mean ± SEM; for sparkles (C), 32 ± 2 vs 37 ± 2, mean ± SEM. (D–G) Representative thresholded images showing cell-wide and local Ca²⁺ transients, 48 hr after treatment with anti MHC I and II or ITC antibody. The area of the imaging field analyzed is indicated. Scale bar = 100 μm.