Authors:H. A. Schreiber, J. S. Harding, C. J. Altamirano, O. Hunt, P. D. Hulseberg, Zs. Fabry, and Matyas Sandor
Granulomas are the interface between host and mycobacteria, and are crucial for the surivival of both species. While macrophages are the main cellular component of these lesions, different lymphocyte subpopulations within the lesions also play important roles. Lymphocytes are continuously recruited into these inflammatory lesions via local vessels to replace cells that are either dying or leaving; however, their rate of replacement is not known. Using a model of granuloma transplantation and fluorescently labeled cellular compartments we report that, depending on the subpopulation, 10–80%, of cells in the granuloma are replaced within one week after transplantation. CD4+ T cells specific for Mycobacterium antigen entered transplanted granulomas at a higher frequency than Foxp3+ CD4+ T cells by one week. Interestingly, a small number of T lymphocytes migrated out of the granuloma to secondary lymphoid organs. The mechanisms that define the differences in recruitment and efflux behind each subpopulation requires further studies. Ultimately, a better understanding of lymphoid traffic may provide new ways to modulate, regulate, and treat granulomatous diseases.
Authors:D. Hunt, J.P. Chambers, A. Behpouri, S.P. Kelly, L. Whelan, M. Pietrzykowska, F. Downey, P.F. McCabe, and C.K.-Y. Ng
Brachypodium distachyon is emerging as the model species for temperate monocotyledonous grasses of the Pooideae, and the genome of the B. distachyon community inbred line Bd21 has recently been sequenced. Here, we report the development of a procedure for the efficient establishment of a cell suspension culture derived from calli. We show that embryogenic potential is maintained in 3-month-old cultures as the cells were positively labelled by the monoclonal antibody, JIM8 which recognizes a carbohydrate epitope often present in arabinogalactan proteins found in the cell walls of cells in embryogenic cultures. Additionally, we were able to regenerate plants from these cell suspension cultures. The cell suspension culture we have established can also be used in studies on plant programmed cell death (PCD). Our results clearly demonstrate that B. distachyon cells can undergo apoptosis-like PCD (AL-PCD) as visualised by the characteristic retraction of the protoplast from the cell wall. As B. distachyon is genetically related to important temperate cereal grass crops like wheat and barley, the ability to utilise cell suspension cultures of B. distachyon to dissect the underlying mechanisms PCD will have important implications for understanding developmental processes in economically important cereal crops.