 B15 is a broad antigen can be subdivided into several split antigens that are often used in characterization.These are B62, B63, B70, B71, B72, B75, B76, B77.B*15 is the largest allele grouping for any known human autosomal locus, identified as of August 2008 there are more than 150 alleles and ~140 amino acid sequence variants from those gene products.