Proliferation and functional responses of bone marrow-derived mast cells after activation

To investigate the behavior of mast cells following activation we have studied IL-3-dependent mouse bone marrow-derived mast cells (BMMC). Proliferation of BMMC presensitized with IgE anti-DNP antibodies was assessed after immunological stimulation with DNP-HSA. Proliferative potential of activated BMMC, as detected by [³H]thymidine incorporation, was similar to that of control BMMC during the first 6 days after activation while on Day 9 activated cells incorporated more [³H]thymidine. Both activated and control BMMC numbers slightly decreased 3-4 days after challenge with antigen and by Day 5 started to increase, reaching a maximum at Day 9. Immunologic activation of BMMC presensitized with IgE antibodies led to a profound loss of responsiveness to rechallenge with the same antigen 2-24 hr and 3-5 days later (70-100% inhibition of β-hexosaminidase release). After l2 days cells were still partially unresponsive (20% inhibition). On the other hand, when BMMC were incubated again with IgE prior to rechallenge, desensitization was less pronounced and was resolved by Day 12. Activation of BMMC with an optimal concentration of thrombin induced only a partial unresponsiveness upon rechallenge 2-4 hr after activation (30% inhibition of β-hexosaminidase release), while activation with calcium ionophore did not induce any desensitization. In both control and experimental BMMC cell-associated histamine remained stable for 12 days after challenge. We conclude that BMMC undergo a period of unresponsiveness which is more pronounced after immunological activation in contrast to nonimmunological ones, similarly to what previously shown for rat peritoneal mast cells.