Histamine release from pulmonary mast cells after lung transplantation in rats.

BACKGROUND AND METHODS

On the assumption that lung mast cells might respond and release histamine after lung transplantation, the number of mast cells and tissue histamine content were investigated for 2 weeks after rat orthotopic left lung isotransplantation (Lewis rat to Lewis rat) and allotransplantation (Lewis rat to Brown Norway rat). The allografts were rejected histologically by day 7 (grade A4).

RESULTS

In the isografts, both the numbers of mast cells and histamine content were lower (p < 0.05) on day 4 but higher (p < 0.001) on day 14 compared with the nontransplanted donor left lungs (control). In the allografts, the numbers of mast cells on day 7 and histamine content on day 1 were lower (p < 0.05) than controls and both continued to be low thereafter. On day 7, the histamine content of the allografts was low (p < 0.05) compared with the level of the isografts. Conversely, no significant change was found in histamine content of the untransplanted right native lungs except for on day 14 after isotransplantation, when the content was higher than the controls, suggesting the possibility of a systemic signal for proliferation of mast cells.

CONCLUSIONS

Our data indicated that degranulation of the pulmonary mast cells and consequent histamine release localized in the grafts occurred under the microenvironment of reimplantation and rejection after rat lung transplantation.