Development and cross-reactive properties of monoclonal antibodies to bovine matrix vesicle alkaline phosphatase

Immunolocalization of alkaline phosphatase in osteoblasts and matrix vesicles of human fetal bone

A monoclonal antibody raised against alkaline phosphatase (ALP) of human osteosarcoma was used to localize this enzyme in human fetal bone tissue. For light microscopy, the presence of alkaline phosphatase in osteoblasts and osteocytes was demonstrated by use of an avidin-biotin immunoperoxidase procedure. Electron microscopic immunolocalization was accomplished with an indirect immunoperoxidase method which revealed a concentration of the enzyme on matrix vesicle and osteoblast plasma membranes. In addition, many vesicular protrusions arising from areas of plasma membrane on the lateral surfaces of adjacent osteoblasts were strongly immunolabeled. Immunostaining for ALP was absent in vesicles which contained fine crystallites. Alkaline-phosphatase-rich matrix vesicles may play a significant role in the mineralization of the extracellular matrix.

Electron microscopic evaluation of the occurrence of matrix vesicles in cartilage

Troubled by variations in the descriptions of shape, appearance, and content of matrix vesicles and the conflicting reports of increased numbers of vesicles in the mineralizing regions of the growth plate contrasted with larger numbers in the resting zone, we embarked on a review of matrix vesicles in the growth plate using a comparison of different fixation techniques. We found matrix vesicles resembling cell debris at all levels of the growth plate, with no particular association with mineral. Lipid bodies surrounded by a membrane of proteoglycan have also been seen in large numbers. The cell debris-like matrix vesicles have been the common finding in reports of digested centrifuged cartilage and may represent cytoplasmic processes. Lipid bodies surrounded by proteoglycan may be similar to the membrane-bound vesicle described by Ali (Fed. Proc., 35:135-142, 1987) and by Bonucci (Clin. Orthod., 78:108-133, 1971).

Bone cell biology: the regulation of development, structure, and function in the skeleton

Bone cells compose a population of cells of heterogeneous origin but restricted function with respect to matrix formation, mineralization, and resorption. The local, mesenchymal origin of the cells which form the skeleton contrasts with their extraskeletal, hemopoietic relatives under which bone resorption takes place. However, the functions of these two diverse populations are remarkably related and interdependent. Bone cell regulation, presently in its infancy, is a complicated cascade involving a plethora of local and systemic factors, including some components of the skeletal matrices and other organ systems. Thus, any understanding of bone cell regulation is a key ingredient in understanding not only the development, maintenance, and repair of the skeleton but also the prevention and treatment of skeletal disorders.

Expression of histocompatibility antigens, transferrin receptors, intermediate filaments, and alkaline phosphatase by in vitro cultured rat placental cells and rat placental cells in situ

Rat placental cells (RPCs) derived from the chorioallantoic placenta of day-12 Holtzman rats were tested for the expression of class I and class II RT I histocompatibility antigens, transferrin receptors, intermediate filaments, and alkaline phosphatase. The binding of mouse monoclonal antibodies to those antigens by RPCs was compared with the binding of the same reagents to rat placental cells in situ. RPCs expressed low levels of class I antigens and failed to express detectable levels of class II antigens. RPCs resisted up-regulation of expression of class I antigens by interferon-gamma, and did not express class II antigens following exposure to medium containing interferon. Transferrin receptors; cytokeratin intermediate filaments, and alkaline phosphatase were universally expressed by RPCs. Taken together with the patterns of expression of the same antigens by rat placental cells in situ, the results suggest that RPCs comprise labyrinthine trophoblast cells. Those cells may provide a valuable new approach for studying the structures and functions of trophoblast cells in vitro.

Purification and partial amino acid sequencing of alkaline phosphatase from rachitic rat epiphyseal cartilage

1. Alkaline phosphatase of rachitic epiphyseal cartilage was purified to apparent homogeneity by sequential application of monoclonal affinity, DEAE-cellulose, and Sepharose CL-6B chromatography. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of the enzyme showed the presence of a dominant band corresponding to a molecular weight of 80,000. 2. The N-terminal amino acid sequence was determined as follows: Phe-Val-Pro-Glu-Lys5-Glu-Lys-Asp-Pro-Ser10-Tyr-Trp-Arg-Gln-+ ++Gln15-Ala-Gln-Glu- Thr-Leu20-Lys-Asn-Ala-Leu-Lys25-Leu-Gln-Lys-?-Asn-Val-Asn-?- Ala-Lys35-?-Ile-?- Met-Phe40-Leu-(Gly?)-Asp-(Ala/Gly?)-Met45-?-Val-?- (Val/Gly?).

Purification and partial amino acid sequencing of rat bone tumor (UMR106) alkaline phosphatase

Cultured rat osteosarcoma (UMR106) alkaline phosphatase was purified to apparent homogeneity by sequential application of polyclonal antibody affinity, DEAE-cellulose, and Sepharose CL-6B chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the enzyme preparation treated with sodium dodecyl sulfate and mercaptoethanol showed the presence of a dominant band (using silver staining) corresponding to a molecular weight of 80,000. The amino acid composition was similar to those of various alkaline phosphatases. The N-terminal amino acid sequence was determined as follows: Phe-Val-Pro-Glu-Lys-Glu-Lys- Asp-Pro-Ser-Tyr-Trp-Arg-Gln-Gln-Ala-Gln-Glu-Thr-Leu- Lys-Asn-Ala-Leu-Lys-?-Gln-Lys-?-Asn-Val-Asn-Ala-Lys.

Immunohistochemical study of alkaline phosphatase in growth plate cartilage, bone, and fetal calf isolated chondrocytes using monoclonal antibodies

Monoclonal antibodies prepared against alkaline phosphatase of matrix vesicles from fetal bovine growth plate cartilage were used to study the distribution of alkaline phosphatase in bovine bone and cartilage. Primary chondrocyte cultures from bovine growth plate cartilage were prepared and expression of this antigen was followed during 3 d long cultured period. Same monoclonal anti-alkaline phosphatase antibodies recognized both osteoblasts in metaphyseal bone as well as proliferating and hypertrophic chondrocytes in growth plate cartilage. Extracellular reaction was observed in lower areas of growth plate cartilage after hyaluronidase digestion of tissue sections. In isolated growth plate chondrocytes strong membrane associated reaction as well as weaker intracytoplasmic reaction were noticed and especially in large hypertrophic cells membrane reaction was clustered showing "capping-like" phenomenon. These results indicates the high similarity of alkaline phosphatase in bone and cartilage and its uneven distribution in chondrocyte plasma membrane.