Higher Molecular Mass Forms of TGFα in Human Milk

Abstract

Transforming growth factor-α (TGFα) has been identified in human milk by various methods, including Western blot analysis (Peptrides et al. 1984; Okada et al. 1991; Connolly & Rose 1988; Wagner et al. 1995). Human milk has been reported to contain higher molecular mass moieties of TGFα (Okada et al. 1991; Wagner et al. 1995), well above the 22-kD form that is predicted from primary translational production (Qian et al. 1993). Okada et al. (1991), in their study of TGFa fractions in human milk, reported that the majority of TGFα in aqueous samples eluted by Sephadex G-50 gel chromatography was of higher molecular mass than the -6-kD mature form. There are numerous reports in other organ systems of higher molecular mass bands appearing that are immuno-reactive with TGFα. In the past, these higher molecular mass bands have been attributed to nonspecific binding (Humphreys-Beher et al. 1994). To verify the existence of higher molecular mass TGFa moieties in human milk, a series of experiments were performed in our laboratory.