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Biomedical subjects

U Melcher

Publications and source records attributed to U Melcher.

45 records · Page 3Linked to original sources
PubMed1976

Cell surface immunoglobulin. XVI. Polypeptide chain structure of mouse IgM and IgD-like molecule.

125I-membrane IgM, 125I-membrane IgD-like molecules, and their constituent chains from iodinated murine splenocytes were characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The apparent m.w. of the heavy chains decreased as the acrylamide concentration was raised. The membrane mu-chain had a slower mobility than did mu-chain from secreted IgM. Unreduced IgM and IgD-like molecules had mobilities consistent with an H2L2 structure. Intact IgD-like molecules were replaced after overnight dialysis by molecules with the properties of HL. Unreduced surface IgM had a slower mobility than that of monomeric IgM obtained by partial reduction of secreted IgM.

Animals↗
PubMed1975

Cell surface immunoglobulin. XI. The appearance of an IgD-like molecule on murine lymphoid cells during ontogeny.

An Ig molecule containing L chains and H chains similar to human delta-chains has been detected on the surface of radioiodinated murine lymphoid cells. Newborn mice have only IgM on their splenocytes. Between 10 and 15 days, the IgD-like molecule appears and increases in amount until 3 mo of age, when it is the predominant cell surface Ig in terms of radioactivity. IgD is found only in peripheral lymphoid tissues and is present in larger amounts on peripheral lymph node cells (approximately 85% of surface Ig) than on splenocytes (approximately 50%). IgD is also present in comparable amounts on cells from both nu/nu and germfree mice, indicating that its expression may be independent of both thymic influence and antigenic stimulation. These studies suggest that there is a switch from cell surface IgM to IgD that occurs during differentiation of virgin B lymphocytes in the spleen.

Age Factors↗
PubMed1975

Cell surface immunoglobulin. XIII. Distribution of IgM and IgD-like molecules on small and large cells of mouse spleen.

The distribution among murine spleen cells of a newly described class of surface immunoglobulin (Ig) with properties similar to human IgD was studied. Splenocytes were separated on the basis of size and the surface Ig on large cells (sedimenting faster than 6 mm/hr in a 1 times G velocity gradient) and small cells (sedimenting between 2.5 and 3.0 mm/hr) was analyzed. Spleen cells from young animals had virtually only IgM on the large cells but had substantial amounts of IgM and the IgD-like molecule (IgD) on small cells. Spleen cells from older animals, which have larger amounts of IgD, had IgM and IgD on both cell types; however, the amount of IgD relative to IgM on the large cells was always substantially less than that on the small ones. These observations taken together with those of other investigators support the hypothesis that a large lymphocyte with surface IgM is the precursor of a small lymphocyte with both surface IgM and IgD.

Animals↗
PubMed1973

An electrophoretic difference between surface and secreted IgM of murine splenocytes.

micro-chains on the surface of murine splenocytes are more heterogeneous on SDS-polyacrylamide gel electrophoresis than both secreted and intracellular micro-chains labeled with [(3)H]tyrosine. No difference in heterogeneity among cell surface, secreted, or intracellular L chains was detected. The possible role of carbohydrate in micro-chain heterogeneity is discussed.

Animals↗