What is the purpose of ABO forward typing in blood typing?

The purpose of ABO forward typing in blood typing is to identify the patient's blood group using known antibodies. This procedure involves mixing a sample of the patient's red blood cells with known anti-A and anti-B antisera. If the blood cells agglutinate (clump together) with the anti-A serum, it indicates that the patient's blood type has A antigens on the surface of the red blood cells. Similarly, if there is agglutination with the anti-B serum, it indicates the presence of B antigens. This method effectively helps determine the specific ABO blood group of an individual by observing the reaction between the specimen and the known antibodies.

In this context, while other options may touch upon related aspects of blood typing, they do not accurately define the forward typing process. For instance, although the presence of antibodies in the patient's plasma can be determined through a different testing method, it is not the main purpose of forward typing. The categorization of antibodies using cell types is more characteristic of reverse typing, which serves a different role in blood grouping. Analyzing serum protein levels would not be relevant to the process of determining blood type, as forward typing specifically focuses on antigens present on the surface of red blood cells.