Increased vascular permeability of Brucella abortus bacilli in the thymus of NZB/W F1 mice

A study of mast cells in autoimmune mice: the proliferative response of autoimmune mast cells to cytokines

To investigate the mechanisms underlying the increased number of mast cells in autoimmune mice, the proliferative response of autoimmune mast cells to cytokines was examined. Bone marrow cells from autoimmune NZB mice produced scarcely any bone marrow derived mast cells (BMMCs) in the presence of interleukin 3 (IL-3), but were able to generate BMMCs when cultured with pokeweed mitogen-stimulated spleen cell conditioned medium (PWM-SCM). In contrast, NZB BMMCs showed very little proliferation in the presence of PWM-SCM, but proliferated strongly when cultured with stem cell factor (SCF). Non-autoimmune NZW BMMCs showed a strong proliferative response to both IL-3 and PWM-SCM, but proliferated weakly in culture with SCF. Autoimmune NZB x NZW F1 (B/W) BMMCs shared the proliferative activities of both NZB and NZW BMMCs, showing strong proliferation in response to IL-3, PWM-SCM and SCF. All strains (including other non-autoimmune strains) except for NZW demonstrated synergism between PWM-SCM and SCF. This study suggests that the strong proliferative response of autoimmune mast cells to SCF plays a major role in, and that other cytokines are partially responsible for, increasing the number of mast cells in autoimmune mice. These mechanisms are discussed in relation to both constitutive and inducible hematopoiesis.

A study of mast cells in autoimmune NZB/W F1 mice: possible relationship between mast cells and increased vascular permeability in the thymus of NZB/W F1 mice

We examined the possible relationship between thymic mast cells and increased vascular permeability in the thymus of autoimmune NZB/W F1 mice. Light-microscopic observation of tissue sections showed that non-autoimmune BDF1 mast cells increased with age. In contrast, autoimmune NZB/W F1 mast cells did not increase in the thymic parenchyma at the age of 9 weeks. However, NZB/W F1 mast cells resumed the age-associated increase from the age of 12 weeks and exceeded the number of BDF1 mast cells at the age of 30 weeks. Blood histamine levels of 9-week-old NZB/W F1 mice were higher than those of BDF1 mice of comparable age. Furthermore, peritoneal mast cells of NZB/W F1 mice were more sensitive to compound 48/80 than those of BDF1 mice. Increased blood histamine levels of NZB/W F1 mice seem to be due to the enhanced histamine release from mast cells. These results suggest a possible correlation between the high histamine levels by degranulation of mast cells and increased vascular permeability in the thymus of NZB/W F1 mice.