It was initially hypothesized that an antibody with this property could be therapeutically useful in stimulating the immune system in immunosuppressed patients. However, "in vitro" and "in vivo" data from animal studies later suggested that administration would lead to preferential activation of regulatory T cells, leading to a net effect of T-cell downregulation. On its website, the company wrote: "A pronounced T-cell activation and expansion mediated by CD28-SuperMAB in animal models is accompanied by the expression of anti-inflammatory cytokines, like IL-10, rather than by the severe cytokine release syndrome of pro-inflammatory mediators induced by other agents that address the TCR complex.". As it turned out, the results of the first trial in humans indicate that this may not always be the case.