Differential effects of chemoattractants on mast cell recruitment in vivo.

Rats were injected with rat recombinant (rr) IL3, rrSCF, rrIL-3+rrSCF, rrRANTES and LTB4. Six hours after subcutaneous injection of rrIL-3 or rrIL-3+rrSCF, there was an increase in mast cell numbers in the skin and spleen. Peritoneal mast cells were recruited following i.p. injection of rrIL-3, but with rrIL-3+rrSCF recruitment was delayed. Immunostaining with a mast cell specific antibody showed that immature orthochromatic mast cells were being recruited. rrIL-3 induced recruitment of mast cells to the peritoneal cavity was blocked by anti-integrin antibodies. Mast cell recruitment depended on the target tissue and the time of exposure to the chemoattractant.