o why abiding combinations of donor and receiver blood types are not suitable?

Red blood cells contained by the different blood types have different signalling molecules on their surfaces. The immune system has antigens against the blood types that are different from the host's type. So the immune system will destroy the red blood cell of the donor, which can make the acceptor very ill. That is why type AB can adopt any other type: it has both A and B types of signalling molecules and O does not have any.
every type of blood has antigens and antibodies in them. so if one type of blood have an antibody that will react with an antigen then the blood will not give support to anything..also rH factors must be compatible as well.
The blood types are:
A, B, AB, and O.
Each red blood cell type (except O type blood cells) has markers present called "antigens" which agree to the body recognize what kind of cell it is.

Type A cells enjoy the A type marker (antigen).
Type B cells have the B type antigen.
Type AB cell have both A and B antigens.
Type O cells have neither A or B antigens.

Now more or less antibodies: Antibodies are made to recognize a certain kind of antigen. If they find the antigen which they are looking for, next the white blood cell which they are attached to will destroy the cell presenting the antigen. So the white blood cells have antibodies which hunt down a definite kind of cell types which have a certain antigen.

If your blood cell have a certain antigen present then you would expect that you body have no antibodies that would attack that specific antigen (or else you would be in trouble).

So, If you have the A antigen then your body have no A antibodies but it does have B antibodies. And vice versa for B.

Type A blood has B antibodies present.
Type B blood has A antibodies present.
Type AB blood have no antibodies present.
Type O blood has AB antibodies present.

So if you are A blood type, and you receive type B blood, then the B antibodies in your blood would direct your white blood cell to attack the B antigens present on the B blood type.

So as it works out A and B can't give to each other. AB can receive blood from anyone and type O can give blood to anyone because type O blood have no antigens which could let it get attacked.

Each blood type may also have a + or - after it. This denotes the presence or fantasy of the 'RhD' antigen. If you don't have this antigen (as in you are a -) then that resources that your body can produce an antibody to attack the 'RhD' antigen. So as it works out, a + can receive blood from a compatible ABO blood type whether they are a plus or a minus; but a - can receive blood from a compatible ABO blood type only if they are a -.

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