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Biomedical subjects

N A Lichtenberg

Publications and source records attributed to N A Lichtenberg.

5 recordsLinked to original sources
PubMed1983

Complement biosynthesis by human bronchoalveolar macrophages.

Complement production by bronchoalveolar macrophages recovered from 8 normal volunteers and 15 patients with a variety of lung diseases was measured functionally and immunochemically. While macrophages from all eight normals demonstrated the capacity to secrete hemolytically active C2 and factor B within 48 hr of culture at consistent rates, bronchoalveolar macrophages from patients secreted C2 and factor B in widely differing amounts, and in some cases, not at all. No functional, secreted C3 was detected from normal macrophage monolayers, although apparently native C3 protein was synthesized and secreted. In contrast, functional C3 was produced by macrophage monolayers from 3 of 15 patients. These findings suggest that complement production by the normal human bronchoalveolar macrophage differs from its progenitor cell, the blood monocyte, and that complement production by bronchoalveolar macrophages may be altered in different pulmonary diseases.

Adult↗
PubMed1982

Complement biosynthesis in human breast-milk macrophages and blood monocytes.

The availability of techniques for establishment of primary, long term monolayers of breast milk macrophages and blood monocytes permitted a direct comparison of biosynthetic functions of human tissue macrophage and its progenitor. In addition to previously described morphological differences, four specific characteristics of the breast milk macrophage were identified: (i) a reduced rate of total protein secretion relative to the monocyte; (ii) abrogation of the 3 day lag in complement secretion regularly observed in blood monocyte cultures; (iii) an increase in the secretion of complement proteins C2 and factor B; and (iv) an increase in the ratio of C2 : factor B secretion. These differences did not result from cell-cell interactions between monocytes and macrophages, stable factors elucidated by monocyte or macrophage monolayers, or heat-stable factors in breast milk. In addition, both monocytes and macrophages synthesized and secreted C3 in an apparently native but haemolytically inactive form. The differences observed suggest that macrophages may modulate local availability of complement proteins in tissues or in the early phase of an inflammatory response.

Cells, Cultured↗
PubMed1980

Covalent binding and hemolytic activity of complement proteins.

We report the inactivation of the third component of complement (C3) by hydroxylamine. C3 hemolytic and covalent binding activities decline with identical kinetics, demonstrating a direct correlation between the two activities. We conclude that covalent, surface-bound C3b is hemolytically active. The inactivation of C3 is first order with respect to hydroxylamine. We also studied C3 inactivation with [14C]methylamine. The inactivation corresponds quantitatively with the labeling of C3 in the C3d domain. The data obtained support the following hypothesis: there is an internal thioester within C3 which becomes highly reactive on activation to C3b, and C3b binds to receptive surfaces by transfer of the acyl function of the thioester to a hydroxyl group on the receptive surface. This proposed model for the reaction of C3 with receptive surfaces also applies to C4, which binds to membrane surfaces covalently and is able to be inactivated by hydroxylamine and methylamine. C5, on the other hand, is not inactivated by treatment with the amines.

Binding Sites↗
PubMed1980

Interaction between the labile binding sites of the fourth (C4) and fifth (C5) human complement proteins and erythrocyte cell membranes.

We have shown that the labile binding site of C3b interacts covalently with receptive surfaces. We report here an analogous study of the interaction between the labile binding sites of the closely related complement proteins, C4 and C5, with sheep erythrocyte membranes. We find that i) C4b binds covalently to cell surface components; ii) the bond between C4b and receptive molecules is hydroxylamine sensitive; iii) the alpha-polypeptide of C4b binds to receptive molecules; and iv) C5b does not interact covalently with cell surfaces.

Autoradiography↗