The habitat, double life, citizenship, and forgetfulness of IgA

Immunoglobulin A (IgA) is the main secretory immunoglobulin of mucous membranes and is powerfully induced by the presence of commensal microbes in the intestine. B cells undergo class switch recombination to IgA in the mucosa-associated lymphoid tissues, particularly mesenteric lymph nodes (MLNs) and Peyer's patches, through both T-dependent and T-independent pathways. IgA B cells primed in the mucosa traffic from the intestinal lymphoid structures, initially through the lymphatics and then join the bloodstream, to home back to the intestinal mucosa as IgA-secreting plasma cells. Once induced, anti-bacterial IgA can be extremely long-lived but is replaced if there is induction of additional IgA specificities by other microbes. The mucosal immune system is anatomically separated from the systemic immune system by the MLNs, which act as a firewall to prevent penetration of live intestinal bacteria to systemic sites. Dendritic cells sample intestinal bacteria and induce B cells to switch to IgA. In contrast, intestinal macrophages are adept at killing extracellular bacteria and are able to clear bacteria that have crossed the mucus and epithelial barriers. There is both a continuum between innate and adaptive immune mechanisms and compartmentalization of the mucosal immune system from systemic immunity that function to preserve host microbial mutualism.

Citizenship and Mental Health Policy in Europe

The problems confronted by people who experience mental disorders are often conceptualised in terms of health and illness. However, these problems extend far beyond the healthcare system, into all areas of human life. Having a psychiatric diagnosis may have a negative impact on every aspect of the individual’s life, leading to the deprivation or limitation of rights in relation to housing, employment, and family life. In this article, some of these problems are discussed within the theoretical framework of debates on citizenship and on human rights. As the context is Europe, reference is made to the recent policy initiatives with the EU, to national and European level consumer organisations and to cases brought before the European Court of Human Rights.