What if we are all chimeras? – After all, one cannot verify that all hundred trillion cells of each of us have the same DNA. Then it is possible that so-called autoimmune disease is actually regular immunity, with one or more sets of cells attacking the other(s). In some cases, the majority cell of the organ or tissue loses out. For example, the majority cell that made up the part of the pancreas that is destroyed in Type I diabetes may have been a minority cell in the body.
Worst case of mosaicism: When twins are born, or multiple embryos are implanted in in vitro fertilization, we may have cells of our sibling or could-have-been-a-sibling, respectively, as well as cells from our mothers and cells from our older maternal siblings.
This could explain why even in the worst cases of autoimmunity, complete obliteration of an organ is rare. If true, then our mosaicism literally extends to every organ.
This could explain the positional specificity of disease – why atherosclerosis starts in one specific spot. It is an “autoimmune” attack that the cholesterol patch is trying to prevent from becoming a hemorrhage. Naturally, doctors blame cholesterol. If cholesterol were the cause of atherosclerosis, all of our arteries would be attacked equally. Why a cavity starts in one specific spot. Why an ulcer starts in one specific spot – the cells were under immune attack; the weakened cells were then killed off by acid plus pepsin after the barrier was eroded by NSAIDS, alcohol, and/or bacteria. Why irritable bowel disease and ulcerative colitis are all initially positional. All “auto”- immune attacks.
This could explain male pattern baldness, vitiligo, and conditions like them.
Each of us can be a chimera – at the very least, we may all have had or still have cells of our mother in us. Some of us may have cells from our older maternal siblings, left over from the after-birth, still alive or even still growing inside the mother (sibling cells may multiply during the immuno-tolerance that pregnancy requires in order not to kill the fetus). They join the developing embryo, and really mess things up.
Everything else being equal, older siblings may thus show less autoimmunity. Primogeniture would have a real genetic basis. Hah. But where older siblings result from fusion of two embryos, they could be even more messed up than their younger siblings.
Could at least some of the excess male homosexuality (male:female homosexual ratios being about 2:1?) be due to cells from the mother or an older sister being the developmental precursors of the cells that control sex drive? Interestingly, the probability of homosexuality goes up as more and more children are born to a mother. Female homosexuality may in some cases result from her older brother’s cells developing into her cells that control sex drive.
The people who suffer most devastatingly from “autoimmune” disease may have the most trouble with their chimeric cells and self-cells battling for immune supremacy.