The BBC has some interesting science programs. I was in the middle of one when Lola wanted to go shopping this morning. I made her wait till it was over. And when we got back, I'm sitting down immediately to write you. Wish you had e-mail. If you do, e-mail me a reply to this letter so I can put your address in our e-mail file. It's so much easier just to write and send instead of write, print, address and envelope, attach postage, and go to the corner to mail. Anythehoo: the BBC program was about a new, still somewhat controversial theory of immunity. As I understand it, the prevailing theory is that the fetus learns self/non-self cell identity in the womb and that after birth everything that is "non-self" is attacked by the immune system. A woman NIH immunology researcher (didn't get her name, but she'd been a professional musician and then a Playboy Bunny before going back to school) wasn't satisfied with the existing theory because she couldn't understand why the normal immune system didn't attack dust particles breathed into the lungs and food absorbed through the walls of the intestines. Watching bubbles pop in her bath one day, and later observing how sheep sheer away from wolves, but allow sheep dogs to come close, the idea popped into her mind that maybe the model was wrong and that we weren't programmed during the fetal stage to distinguish self and non-self, She knew that when normal cell death happens, dendritic cells merely shrivel, with all their inner constituent material drying up. But when a virus or bacterium kills a cell, it explodes and the inner stuff floods adjoining cells. She postulated that there is a previously unrecognized organella in each cell that signals "danger", and that when released, this triggers an alert to the immune system sending T-cells to the scene of attack. Since at least in the early stages, cancer cells are live cells which cause no immediate danger, there is no signal to the T-cells. She says rejection isn't automatic. It is caused by the trauma of surgery which releases "wolf" danger signals from the injured cells of the transplant material -- liver, heart, lungs, pancreas, etc. Her work is supported, according to the BBC program, by the studies of an Australian scientist who found he could transplant pancreases without rejection if they'd first been immersed in an oxygen rich bath overnight. Initially he could find no reason for this and his papers reporting it were rejected by journal after journal. It is now thoght that the oxygen destroys the "wolf" organella released by the cells destroyed by the surgery involved in removing the pancreas and then re-implanting it. The BBC says there've been other confirmatory results. It seems that the initial signal alert the T-cell, then a second signal directs the T-cell to migrate to the site of the danger. They've learned to abort the second signal. As a result they've succeeded in grafting skin from mouse to mouse without rejection. Indeed, someone has just succeeded in an inter-species graft -- a rat heart into a mouse. And it survived a normal lifetime. The next stage has been to inject killer bacteria into cancer sites, causing cell destruction and release of "wolf" signals activating T-cells to attack early cancer as an "enemy" The program includedthe story of an Englishman with advanced skin cancer who is currently being injected with a special variety of bacteria which migrate selectively to cancer cells, killing them, and activating T-cell response. While it's too early to speak of a "cure", the guy is in remission. Wow. What a story. I know there are "cancer cures" reported all the time. Always prematurely. But I though I'd go to the horse's mouth to make sure you were abreast of this new theory of immune reaction and to ask what you think of it. One unresolved question which has occurred to me is, what about incompatible tissue types and blood types. Doesn't that matter any more? Or are they separate issues? Can you think of how alien blood may send "wolf" signals to the T-cells of the recipient. Blood cells don't rupture during transfusion -- or do they? Could circulating oxygen through donor blood make it good for any recipient. This would sure help solve the problem of finding compatible blood donors. At any rate, the BBC story ended by showing an experiment where they'd succeeded in an inter-species implant of a rat heart into a mouse without rejection. Think what this might mean in terms of resolving the problem of insufficient human organs. We could use gorilla hearts, or livers, or panreases. Young scientists are said to be ecstatic. The new paradign answers many previously unresolved questins. Old-timers are said to be more dubious. Do get back to to me on this. I can hardly hold my breath for the rest of the story. Hearty greetings from Lola to both you and Joyce. As ever, Dave Timmins