The "ABO system" is the most important blood-group system in human-blo are produced in the first years of life by sensitization to environmental substances such as food, bacteria, and viruses.
The "ABO system" is the most important blood-group system in human. Blo are produced in the first years of life by sensitization to environmental substances such as food. Blo are produced in the first years of life by sensitization to environmental substances such as bacteria. Blo are produced in the first years of life by sensitization to environmental substances such as viruses.