TISSUE-DEPENDENT DIFFERENCES IN THE ASYNCHRONOUS APPEARANCE OF MAST-CELLS IN NORMAL MICE AND IN CONGENIC MAST CELL-DEFICIENT MICE AFTER INFUSION OF NORMAL BONE-MARROW CELLS

The time courses of the appearance of tissue mast cells in six sites w ere compared in normal WBB6F(1)- +/+ mice (+/+) and in congenic mast c ell-deficient WBB6F(1)-W/W-v mice (W/W-v that received an intravenous infusion of bone marrow cells from +/+ mice (BM-->W/W-v). As assessed by morphometric analysis of Carnoy's solution-fixed, methylene blue-st ained tissue sections, the density of mast cells in the stomach mucosa , stomach submucosa, and spleen of +/+ mice reached maximal levels by 8 weeks of age, whereas the density of mast cells in the skin, extrapa renchymal airway walls, and lung parenchyma did not reach maximal leve ls until 18 weeks of age. When 8-week-old W/W-v mice were infused with 2 x 10(7) bone marrow cells from +/+ mice, mast cells appeared in the stomach mucosa and submucosa after 25 weeks, in the spleen and extrap arenchymal airway walls after 5 weeks, and in the lung parenchyma afte r 10 weeks. Twenty weeks after bone marrow infusion, the mast cell den sities in the spleen, stomach mucosa, and stomach submucosa were seven -, 13-, and five-fold greater, respectively, than those in age-matched +/+ mice, but were eight-, two-, and five-fold lower in the skin, ext raparenchymal airway walls, and lung parenchyma, respectively. Thus, t hose tissues that in +/+ mice reached maximal mast cell densities earl ier exhibited abnormally high mast cell densities in BM-->W/W-v mice, and those that reached maximal mast cell densities later in +/+ mice h ad abnormally low mast cell densities in BM-->W/W-v mice. Immunologica l and inflammatory responses are often compared in W/W-v and BM-->W/W- v mice to assess mast cell dependency. Our results indicate that the c apacity to restore a mast cell-dependent response in a particular tiss ue of the latter mice may relate to the local mast cell density and wh ether the immunological challenge activates mast cells only in that ti ssue or systemically with attendant widespread release of proinflammat ory mediators.