i have been wondering about the blood groups consider this when a person has the blood group A ..he has antibodies for the blood group B how is this possible..when tat person is previously not injected with blood group b?
The immune system has antibodies for over a billion different types of external chemical structures (antigens). It is not that the people with blood type A have antibodies specifically against blood type B. It is just that blood type B antigens are different enough from endogenous blood type A that the process of "weeding out" self-antigens has not removed antibodies against blood type B. In the thymus of all mammals, all immune cells that react with self antigens (ie, blood type A in people that have blood type A) are destroyed so they don't attack "self" cells.
wat abt cross reactivity??? i read somewhere that " cross reactivity is often observed among poly saccharide residues. The ABO blood group antigens for eg are glycoprotiens expressed on RBCs. Subtle differences in the terminal sugar residues distinguish the A & B blood gp. antigens. An individual lacking 1 or both of these antigens will have serum antibodies to the missing antigens. A type O individual thus has anti A and Anti B abs. a type A has ab antiB and a type B individual has a type AntiA. Cross reactivity is the basis for the presence of these blood gp antibodies which r induced in an individual, not by exposure to RBC antigens but by exposure to cross reacting microbial antigens present on common intestinal bacteria. These cross reacting microbial antigens induce the formation of antibodies in the individuals lacking these antibodies on RBC cells. The blood gp. antibodies although elicited by microbial antigens, will cross react with similar oiligosaccharides on RBC." Plz explain...
I don't know where you read that, but no microbial antigens are even slightly similar to human antigens, given that we are separated by at least 1 billion years of evolution. The fact that someone with blood group 'A' rejects blood from someone from group 'B' is simply a testament to the extraordinary versatility of our immune system. Although the differences in the glycoproteins indicating our blood types are subtle, they are sufficiently different that our immune system can recognize them as 'foreign.' As far as microbial antigens go (and this is something I work with on a daily basis), they are sufficiently different that, in many cases, we do not need the adaptive immune response (eg, antibodies and B cells), but simply the innate immune response (macrophages and dendritic cells) to respond to foreign antigen (eg, lipopolysaccharide and CpG methylated DNA). Given that microbial physiology is so different from our own, it is (almost) impossible that antibodies against blood groups are initiated by microbes.
well...i got that information from a text book on immunology...its supposed to do something with cross reactivity... ur explination to why the antibodies to our own blood are destoyed actually sortof cleared my doubt...i was just wondering if the method stated in the text book was also valid ...thats all and its not that I am "advertising " for monoclonal antibodies!
Maybe you can help me with a question. Since all mammals have a thymus, do all mammals have more than one blood type? I know that dogs have at least 9, cats 3, elephants 2, horses 7, cows 10, pandas at least 2, and they have discovered over 50 different antigens by experimenting with guinea pigs and rats. I would assume that all mammals do. But what about other non-mammals (reptiles, amphibians, insects, fish) and all vertebrates? I know there is little research done in this area but I just read an article that says that zebrafish blood cells "closely resemble their mammalian counterparts, and arise from a process very similar to the hematopoietic pathway seen in mammals."
Isn't there a blood group called AH? I think only 3 people in the world are known to have it. Correct me if I'm wrong.
Yes. It appears there is a rare Ah blood type. I did a quick search on google and the first thing that came up referred me to an article entitled "Trilogy of Fallot with extremely rare blood type Ah (Bombay blood subtype)," by Noguchi K, Miki N, Tatemichi K, Minami K, Tatsuta K., Jpn Circ J. 1975 Jul;39(7):852. This article is referenced through PubMed for MEDLINE but it is written in Japanese. Nevertheless, I can order it through our university and have someone translate it for me. Might take a while. What is "Trilogy of Fallot"? But AH is also a blood type in cows: "the factors A and H occupy different areas on the chromosome strands. So, an animal may have A, or H, or both..." see "About Blood Typing" by IMMGen at www.immgen.com/Services/Verification/Bloodtyping.html
Got it. Trilogy of Fallot is a circulatory disorder: pulmonary valve stenosis (a narrowing or stricture of the heart valve) combined with an "atrial septal defect with right ventricular hypertrophy." Remember though that the use of capital or small letters is important in blood groupings. The rare blood type in humans is referred to as Ah not AH. AH is the one found in cows. Do you think maybe you're making a typo?
I hope somebody has a better answer than I do, but I'm sure it has something to do with the extent of crossbreeding and genetic drift in the evolution of the subspecies. That's just a guess, but there are a lot more subspecies (breeds) of dogs, horses, and cows, than their are of elephants and cats, and they have a corresponding increase in the number of blood types. I know that that doesn't answer your question but I can probably post a better reply tomorrow after I ask my biology prof.
Thanks, I'd appreciate an answer! I myself at first thought it's something to do with the genetic drift, but it seems that these blood groups are too globally mixed and not enough based on a particular territory. Or maybe they got mixed at a later date. I'm no biologist so please excuse if this is not so.
A better answer is this. Blood types are determined by the three different alleles at one locus or point on the DNA chromosome. Remember, every gene has at least and usually always only two alleles. When humans mate, we transmit one of our two alleles and the person you are mating with does the same. This is why no two people look alike: the chromosomes are mixed 50-50 from each. In scientific terms, this means we are "dioecious," meaning "having two sexes. Some plants, and animals, are "monoecious," meaning that both the male and female gametes are within the same individual. This is why many species of plants and smaller animals like protists and algae look identical: there's no mixing of the genes from seperate individuals that would give them more diversity. The environment changes the organism and gives each individual a physical (phenotype) difference that eventually can put pressure on the corresponding gene (genotype) to change. And then there are also genetic mutations that can be passed on to alter the species considerably. The Ah blood type is probably the result of a mutation. But blood types are also the result of different antigens (agglutinogens) that work with the bodies immune system to clump the blood together in responce to an antibody. So the variations in antigens is probably due to the bodies immune system to fight off different variations of antibodies: antigens stimulate the body's immunological responce which then produces its own antibodies, and vice versa. Overtime, both antigens and antibodies mutate or become resistant to the "perceived" foreign invaders. This is what happened in the SARS virus in China that caused it to jump from animals (cervid cats) to humans, and is what is causing the Asian Bird Flu to now do the same.
Actually I think the blood groups are not mixed globally enough. Check out the percentages of the different blood types according to ethnic background: Bloodtype Race A B O AB U.S. 42% 10% 45% 3% Chinese 31% 28% 34% 7% Navajo Indian 24% 0 76% 0 Blackfoot Indian 76% 0 24% 0 And you see the same type of variation in different percentages in different breeds of dogs and cats.
You know, if you look at the percentages, you're probably right in saying that the more globally mixed they are, the more blood types. Native American Indians (Navajo and Blackfoot) don't even have any B or AB bloodtypes and the most variation is seen in Chinese. China, way before America became a melting pot, was, and still is, composed of a hundred or more different ethnic groups. Throughout their entire 5,000+ year history they were continuously being invaded by foreignors (hence the reason for the Great Wall of China) that were then assimilated into the overall population. So it is no surprise to see that Chinese have the most variation in blood types.
I doubt that invertebrates have blood groups that mean anything very significant. Their immune systems, such as they are, are very "primitive" compared to ours. So if, for some unknown reason, you wanted to do a blood transfusion between horseshoe crabs, there probably wouldn't be any immunological response, irregardless of how genetically different the two crabs are. Invertebrates probably have different blood groups in the sense that there are different alleles for surface proteins on their cells (like our A/B/O) - their immune system just wouldn't be able to recognize the difference. And as far as blood groups in mammals go, I think the number of groups is largely a function of how long the particular mammal species has been around and the number of organisms in that species. Humanity underwent a bottleneck about 400,000 years ago, which severely limited our relative genetic diversity (and number of blood groups). Things like mice are everywhere and have had millions of years to gain different blood groups by mutation and genetic drift.
