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Summary.We have demonstrated that 44% of myelodysplastic syndrome (MDS) patients with cytopenia have a haematological response to antithymocyte globulin (ATG). Three ATG responders and two non-responders with refractory anaemia were further studied for lymphocytemediated inhibition of bone marrow using a standard CFU-GM assay. In responders, peripheral blood lymphocytes (PBL) added at a 5:1 ratio suppressed CFU-GM by 54 Ϯ 9% (P ¼ 0·04) and was reversed by ATG treatment. Pre-treatment marrow depleted of CD3 lymphocytes, increased CFU-GM by 32% (P ¼ 0·02) in an ATG responder, but not in a nonresponder. CD3 lymphocytes from 6-month post-treatment marrow did not inhibit pre-treatment CFU-GM, indicating ATG had affected the T cells. Pre-treatment marrow depleted of CD8 lymphocytes, increased CFU-GM by 60% (P ¼ 0·01) and 49% (P ¼ 0·03) in two ATG responders, but not in a non-responder. Inhibition required cell-cell interaction through MHC I. TCR Vb families, analysed by SSCP, changed from clonal to polyclonal in one ATG responder after 6 months, but clones persisted in a non-responder. These results indicate patients with refractory anaemia who respond to ATG have CD8 T-cell clones that mediate MHC-I-restricted suppression of CFU-GM which are replaced by polyclonal T cells that do not suppress CFU-GM after ATG treatment.

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The importance of resilience for tourism organizations facing crises and disasters is indisputable. Yet little is known about how these organizations become resilient. This paper proposes that dynamic capabilities provide a mechanism that enables tourism organizations to respond to disruptive environmental changes through a process of routine transformation, resource allocation, and utilization. The resulting theoretical framework takes a processual view to show how an organization's existing operational routines transform into new ones that are resilient to disruptive events, enabled by dynamic capabilities and slack resources. The paper outlines six research propositions and suggests methods for future empirical research.