The present invention provides a method for producing a transgenic (Tg) non-human animal capable of developing an enhanced humoral immune response against an antigen as compared to a non-transgenic control animal of the same species, comprising introducing into said non-human animal a genetic construct providing for enhanced MHC class I-related neonatal Fc receptor (FcRn) activity. Also provided a Tg non-human animal comprising a genetic construct providing for enhanced FcRn activity, as well as the use of such animal in a non-therapeutical method. Therapeutic genetic constructs and methods are also provided. The present invention further provides methods for producing immunoglobulins.