Identification and tissue localization of an eosinophil 17 kDa protein accumulating in rat uterus upon estradiol treatment

Analysis of pregnancy-associated major basic protein levels throughout gestation

Previous studies have shown that MBP levels rise before labour and have suggested the use of pMBP levels as a predictor of labour. We hypothesize that pMBP levels show a common pattern in pregnant women including a late third trimester rise in pMBP which predicts the onset of labour. Serum pMBP levels were measured throughout gestation in 112 pregnant women. We then analysed the relationship of pMBP levels to the time of labour onset, and to other features of pregnancy. An exponential increase in pMBP levels was seen early in gestation from weeks 5 to 21 in all pregnant women. In total, 79 per cent of the women showed rises in pMBP of > or = 25 per cent above baseline during the third trimester. pMBP levels were shown to be associated with placental weight, multiple gestation, and parity. pMBP levels could not, however, be used to form a precise model for the prediction of labour. The role of pMBP in pregnancy remains unclear.

Pro-major basic protein has three types of sugar chains at the pro-portion

The amino-acid sequence of purified recombinant pro-major basic protein from Chinese hamster kidney cells was determined to verify the primary structure and glycosylation sites. Reduced and S-carboxamidemethylated protein was first digested with Achromobacter proteinase I. Each peptide was characterized by amino-acid analysis and amino-acid sequence analysis. We could identify all the peptides which were expected from the pro-major basic protein cDNA sequence. Sequence analysis and deglycosylation study revealed that Ser-8, Thr-9, Ser-46 and Asn-70 were glycosylated. The results indicated that proMBP has three types of sugar chains, O-glycoside, N-glycoside and glycosaminoglycan, in the pro-portion.

Immunohistochemical localization of the eosinophil major basic protein in the uterus horn and cervix of the rat at term and after parturition

Distribution of the eosinophil major basic protein (MBP) was studied in the rat uterus horn and cervix by means of immunohistochemistry using an antiserum raised against rat MBP. Various hormonal contexts were investigated: pre- and post-parturition, the estrous cycle, and ovariectomy followed by hormonal treatment or without treatment. MBP was detectable in the cervix as early as 12 h post-partum, appearing in the stroma close to the myometrium. The MBP had spread throughout the stroma toward the luminal epithelium after a few days. In contrast, no MBP was seen in sections of the corresponding pre- and post-partum uteri and in the pre-partum cervix. In cycling rats, MBP was distributed equally in the cervix and uterus and was more abundant during proestrus and estrus. In ovariectomized rats subsequently treated with progesterone, no MBP was detected in the cervix or uterus. In the cervix of ovariectomized rats treated with estradiol, MBP first appeared in the muscle layer situated between the two cervical lumina and then reached the stroma; within a few days only the stroma was stained. Inversely, in the uterus MBP-staining first appeared in the stroma. In conclusion, analysis of the distribution of MBP in rat uterus revealed a marked difference in the response of the cervix and horn to a hormonal environment.