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ABO blood grouping help - (Mar/26/2013 )

I carried out a standard forward and reverse ABO blood group on a sample and they were negative for agglutination in groupings in every test (Anti-A, anti-B, anti-A+B, A cells and B cells) and the results are correct according to my prof.

I have no idea what this means and I was wondering if someone could help. The only explanation I can think of is that the patient has some sort of leukaemia which results in antigen shedding/abnormal immunoglobulin production.

Any help? )


Some ideas on this site.


if it doesn't react to anti-a, anti-b or anti-ab (therefore, absence of antigen), and the choices are abo, then what does that leave?


mdfenko: I think this would be relevant if only forward testing was done, but reverse testing (plasma antibodies of patient) would in case of 0 agglutinate both A and B cells as a crosscheck. If it's all nonreacting, some of the results have to be false negative.


antibodies will only be present if the individual had previously been exposed to the antigen (eg if the mother's blood contained the antigen or if the individual had had a transfusion with the wrong blood type).


No, actually almost all people have naturally occuring IgM antibodies to the antigens they lack, without need to encouter them in any way. That's why it can be used extensively as a check for the forward method.


from wikipedia:

IgM antibodies appear early in the course of an infection and usually reappear, to a lesser extent, after further exposure. IgM antibodies do not pass across the human placenta (only isotype IgG).

These two biological properties of IgM make it useful in the diagnosis of infectious diseases. Demonstrating IgM antibodies in a patient's serum indicates recent infection, or in a neonate's serum indicates intrauterine infection (e.g. congenital rubella).


IgM in normal serum is often found to bind to specific antigens, even in the absence of prior immunization. For this reason IgM has sometimes been called a "natural antibody". This phenomenon is probably due to the high avidity of IgM that allow it to bind detectably even to weakly cross-reacting antigens that are naturally occurring. For example the IgM antibodies that bind to the red blood cell A and B antigens might be formed in early life as a result of exposure to A- and B-like substances that are present on bacteria or perhaps also on plant materials.

IgM antibodies are mainly responsible for the clumping (agglutination) of red blood cells if the recipient of a blood transfusion receives blood that is not compatible with their blood type.

if there's been no exposure to blood antigens (or bacteria with proteins that mimic them) then there should be no igm. maybe the individual from whom the blood sample was drawn is one of the not "almost all" (glutamate's professor did say that the results were correct)?