Contact-dependent immune suppression can occur by engagement of MHC class I molecules on CD8+CD28- suppressor cells with immunoglobulin-like transcript (ILT2 and ILT4) inhibitory receptors on DCs. Blocking of both MHC Class I and ILTs by specific antibodies can reverse immunosuppression [ 65 ]. Similarly binding of c-type lectin receptors or Killer Immunoglobulin-like Receptors (KIRs) to MHC Class I ligands inhibit NK cell function (Wagtmann et al , 1995; D'Andrea et al , 1995; Lazetic et al, 1996; Carretero et al, 1997;Brooks et al, 1997). In addition, the expression of co-stimulatory molecules, such as B7H1 on tumor cells and inhibitory DCs and T cells can inhibit T cell activation and proliferation (Cuiel, et al., 2003).
“But the benefits of this compound don’t just stop at directly inducing programmed cell death (apoptosis). It also inhibits angiogenesis (the ability of tumors to grow new blood vessels to get their food) and stops cancer metastasizing by impeding cell migration and invasion. Even more intriguing is the ability of frondoside A to activate our immune system’s natural killer cells to attack cancer cells. This has been shown for breast cancer in particular but may also apply to all cancers, because it involves the immune system and not cancer cells directly. This may partially explain why frondoside A was so effective at shrinking lung tumors in mice that it rivaled chemo drugs in performance.”
(This program is no longer available for online streaming.) Over the millennia, thousands of creatures have developed that most sophisticated of biological and chemical weapons: venom. These complex chemicals can scramble your brain signals, paralyze your muscles, puncture your blood cells, even begin digesting you from within. But nature's most potent toxins might also contain the keys to a new generation of advanced drugs. Such drugs might help doctors treat heart attacks, cancer, diabetes, and other serious illnesses. Follow NOVA crews as they join scientists on a dangerous quest to track down and capture the world's most venomous animals—to find out both how they can kill us, and how they can save us.