Localization of a molecule immunochemically similar to eosinophil major basic protein in human placenta.

Abstract

The eosinophil granule major basic protein (MBP) 1 is an arginine rich, highly basic, 9,300 dalton protein, which forms the crystalloid core of the granule (1-3) and is present in small amounts in basophils (4). MBP is toxic to parasites (5-7) and is deposited onto the surface of damaged microfiliariae in Onchocerca volvulus infestation (8). MBP is also toxic to cells (5, 9) and causes desquamation of respiratory epithelial cells in vitro (10, 11). Finally, MBP triggers histamine release from human basophils and rat mast cells (12).We have recently reported that MBP circulates in the blood of pregnant women at levels 10 to 20 times those found in normal, nonpregnant women (13). The levels of this immunoreactive MBP increase during the first 3 mo of gestation, plateau during the second and third trimester, and decrease sharply following parturition. Eosinophilia is not present during pregnancy, and other eosinophil-related proteins are not elevated in the sera of pregnant women. Chromatographic analysis of sera from pregnant women indicates that the immunoreactive MBP has an apparent molecular size greater than the molecule purified from the eosinophil granule. These observations suggest that the immunoreactive MBP molecule in the sera of pregnant women is derived from a source other than the eosinophil. Here we report that immunoreactive MBP is localized in placenta, intracellularly in placental X cells and placental-site giant cells and extracellularly in anchoring villi and at the choriodecidual junction. Materials and MethodsTissue. Placental tissue was prepared in the delivery suite for fixation and embedding. First and second trimester medical abortion tissues were kindly provided by Dr. M. Hansen, Minneapolis, MN. Other placental and gestational tissues were available from the Department of Pathology of the Mayo Clinic. Table I lists the types of tissues and the number of blocks examined from each.

Placental Regulation of Peptide Hormone and Growth Factor Activity by proMBP1

“…MBP is highly basic and toxic to both mammalian cells and parasites, and it functions in the defense against invading parasites. Hence, it was a surprise when a protein immunochemically similar to MBP was detected in the placenta and in the circulation of pregnant women [1,2]. The protein was of higher molecular weight compared to MBP isolated from the eosinophil granules and was suggested to be disulfide bonded to other proteins [3].…”

The proform of eosinophil major basic protein: a new maternal serum marker for Down syndrome

“…The proform of the most abundant protein constituent of the specific granule of the eosinophil leukocyte, the major basic protein (MBP) (Gleich and Adolphson, 1986), is also synthesized by the placenta (Maddox et al, 1984;Bonno et al, 1994a,b) and secreted into the maternal circulation. MBP antigen has previously been determined immunochemically (Maddox et al, 1983;Wasmoen et al, 1987Wasmoen et al, , 1989Wasmoen et al, , 1991Wagner et al, 1993).…”

Identification of basophils by a mAb directed against pro–major basic protein 1

“…Similarly, the J175-7D4 specifically stained insect cells (Fig 3) and CHO cells (data not shown) engineered to express human rproMBP1. J175-7D4 also stained human placental tissue, previously shown to express proMBP1 33,45,46 (data not shown). Notably, J175-7D4 typically produced more intense indirect immunofluorescence staining than J163-15E10.…”