New chicken Rfp-Y haplotypes on the basis of MHC class II RFLP and MLC analyses

New chicken Rfp-Y haplotypes were determined by the use of restriction fragment length polymorphism (RFLP) and mixed lymphocyte culture (MLC) in four different chicken haplotypes, B ¹⁵ , B ¹⁹ , B ²¹ , B ²⁰¹ . The RFLP polymorphism was mapped to the Rfp-Y system by the use of a subclone (18.1) which maps near a polymorphic lectin gene located in the Rfp-Y system and DNA from families with known segregation of the implicated RFLP polymorphism. For the first time it is shown that major histocompatibility complex class II genes in the Rfp-Y system have functional implications. Sequence information of the B1 domain of the proposed Rfp-Y haplotypes was obtained which supported the functional data.