Anti-granulocyte antibody suppression of active and passive anaphylactic shock in WBB6F1-W/Wv mice

. Our previous study revealed that anaphylac tic shock can be produced in WBB6F1-W/W v (abbreviated as W/W v ) mice. Because they are congenitally deficient in mast cells, we are certain that some other cell types are involved as mediator sources. In the present study, with the aim of examining the role of circulatory granulocytes, the effect of monoclonal an tibody to a mouse granulocyte antigen, Gr-1, upon active and passive anaphylactic shock was tested in W/W v mice using several mast cell-bearing strains as references. An intravenous injection of 40 μg of anti-granulocyte antibody one day before the antigen chal lenge produced a marked decrease in neutrophils and nearly complete abolition of lethal shock in W/W v mice regardless of the sensitizing method. Both pre vention of shock and reduction of neutrophils lasted for three days after the treatment with the antibody but not for six days. From these results, a reasonable conclusion would be that circulating Gr-1 + cells (predominantly composed of neutrophils) are the major mediator source. Reference experiments using mast cell-bearing strains revealed that the suppressive effect of anti-granulocyte antibody was also observed against active anaphylactic shock in C3H/HeN mice but not against active and passive anaphylactic shock in the other mice.