antibodies against A, B and RH antigens?

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In most developed and developing countries, hospitals are equipped with Accredited blood banks, and regular blood donations, help to maintain a supply of most of the blood needed for transfusion to recipients.

Hence blood transfusions are done with donated blood that is an exact match with the recipient's type and Rh factor. Even then, small samples of the recipient's and donor's blood are mixed to check compatibility in a process known as crossmatching. Transfusion is avoided in case any form of clotting is seen during the process.

Blood Group O - has neither A nor B antigens on red cells, but both A and B antibodies are in the plasma.
Though, type O negative blood is considered as the universal blood donor type, various antibodies present can result in serious reactions during a transfusion. Hence this type of transfusion is done rarely, and only when the recipient is in critical life threatening conditions, when the risk of transfusion reactions is low and acceptable.
In addition, risk of transfusion reactions are more when the whole blood (Red cells + Plasma) is transfused. Hence in cases when compatible blood is not available, and O negative blood has to be transfused, transfusion reactions can be minimized by transfusing only Packed red cells (in which the plasma is removed).

I hope this helps.