In recent decades, long-term use of hormone replacement therapy (HRT) has been widely and heavily promoted as a prophylaxis against heart disease and other illnesses. Millions of women have taken these medications based on their physicians’ recommendations, which were made despite the absence of data from clinical trials demonstrating benefit. Belief in a protective effect of HRT against heart ...

require two signals for full activation, but the mechanisms of how these signals function have been only recently elucidated (1). The first signal is provided by the T-cell receptor after interacting with the MHC/antigenic peptide complex. This so-called “signal one” confers antigen specificity to the immune response but alone is insufficient for full T-cell activation. Indeed, T cells receivin...