Oh God, where to find this word: immunostat?

immunostat =?

Context:

Currently, B cells are being implicated in the pathogenesis of various autoimmune diseases hitherto attributed essentially to T cells, with type 1 autoimmune diabetes being a notable example. All this has raised the possibility of ‘rebalancing’ the immune system by B cell depletion [23]. Such therapies that reduce B cell competence may reduce autoreactivity by resetting a postulated immunostat.