We describe the generation of five sheep transgenic for a fusion of the ovine beta-lactoglobulin gene promotor to the human alpha 1-antitrypsin (h alpha 1AT) genomic sequences. Four of these animals are female and one male. Analysis of the expression of h alpha 1AT in the milk of three of these females shows that all express the human protein at levels greater than 1 gram per liter. In one case initial levels exceeded 60 grams per liter and stabilized at approximately 35 grams per liter as lactation progressed. Human alpha 1AT purified from the milk of these animals appears to be fully N-glycosylated and has a biological activity indistinguishable from human plasma-derived material.

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We have recently described the production of large amounts (< or = 65 grams per litre) of enzymatically active human alpha 1 antitrypsin in the milk of transgenic sheep (Wright et al., 1991). Here, we describe in more detail the expression of the human protein in the milk of these animals throughout the lactation period. Human alpha 1 antitrypsin is also found at much lower levels in the plasma of transgenic ewes before, during and after lactation. It is also detected in male plasma at very low levels. We have previously shown human alpha 1 antitrypsin purified from transgenic sheep milk to be indistinguishable from commercially available human plasma derived alpha 1 antitrypsin in terms of gross sugar content and in vitro activity. Here we extend this comparison to more detailed analyses of glycosylation state, amino-terminal sequence, pI value, and molecular weight determination by mass spectrometry.