Abstract: Methods of producing and using recombinant soluble HLA-G are provided. This recombinant soluble HLA-G alters immune responses to tissues, organs, fetuses, and embryos which are genetically distinct from the organism receiving or possessing such antigenic material. Preferable forms of this protein include sequences having at least 70% sequence homology with naturally occurring forms of HLA-G. Specifically, each recombinant form of HLA-G produced and used by the present methods must include a sequence having at least 70% sequence homology to introm 4 expressed by the HLA-G gene and at least one sequence having at least 70% sequence homology to one of the &agr; domains expressed by the HLA-G gene. Preferable forms of the present invention include one isoform which includes the &agr;1 domain, the &agr;2 domain, the &agr;3 domain, and intron 4, and a second isoform which includes the &agr;1 domain, the &agr;3 domain and intron 4.