Murine IgM

Shibuya, N., Berry, J. E., and Glodstein, I. J., (1988). One-step purification of murine IgM and human a2-macroglobulin by affinity chromatography on immobilized snowdrop bulb lectin. Arch. Biochem. Biophys. 267, 676-680. 

Yellen, A J., et al. Signaling through surface IgM in tolerance-susceptible immature murine B lymphocytes. Developmentally regulated differences in transmembrane signaling in splenic B cells from adult and neonatal mice, J Immunol., 146, 1446, 1991. 

Cacciuttolo MA, Patchan M, Harrig K, Allikmets E, Tsao EL Development of a high yield process for the production of an IgM by a murine hybridoma. Biopharmaceutics 1998 44. 

MBP is present in various mammalian sera and activates the complement system through the classical pathway. It also specifically binds to murine monoclonal IgM and, hence, can be used to purify IgM MAb from mouse ascitic fluids. The binding reaction is calcium-dependent, so that IgM can be specifically eluted with a buffer containing a calcium chelator (e.g., EDTA). 

Yi, A.K., Hombeck, P., Lafrenz, D.E. and Krieg, A.M. (1996b) CpG DNA rescue of murine B lymphoma cells from anti-IgM-induced growth arrest and programmed cell death is associated with increased expression of c-myc and bcl-xL. J. Immunol., 157, 4918 1925. 

Greenman, R. L., Schein, R. M. H., Martin, M. A. etal. (1991). A controlled clinical trial of E5 murine monoclonal IgM antibody to endotoxin in the treatment of gram-negative sepsis. JAMA 266, 1097-1102. 

Isoelectric precipitation and acid precipitation are also used to separate antibodies. Isoelectric precipitation (also called euglobulin precipitation) uses the solubility properties of a protein near its isoelectric point.69 When a concentrated protein solution in a low ionic strength buffer is titrated to its isoelectric point, it precipitates very slowly. Table 4 shows a balance of a process for purification of murine monoclonal IgM antibodies.70 The success of precipitation can be followed by the cumulative IgM content in the centrifugate and the sediment. The procedure is very gentle, but very sensitive to environmental conditions. 

Garcia-Gonzalez, M., Bettinger, S., Ott, S., Olivier, P., Kadouche, J., and Pouletty, P. (1988). Purification of murine IgG3 and IgM monoclonal antibodies by euglobulin precipitation.. Immunol. Methods 111, 17-23. 

Thrombocytopenia after a second exposure to abciximab in nine patients showed that each had a strong immunoglobulin IgG antibody that recognized platelets sensitized with abciximab (23). Five patients also had IgM antibodies. Thrombocytopenia occurred four times as often as after the first exposure. The mechanism is not understood, but these findings suggest that it may be antibody-mediated. These antibodies were also found in 77 of 104 healthy patients, but in the patients the antibodies were specific for murine sequences in abciximab, causing the hfe-threatening thrombocytopenia. 

Isotype commitment seems to be the rule particularly for transformed cells. In the murine pre-B cell line 18-81 and some other pre-B cell lines switching occurs from u to ylb at high frequency [27] whereas 1.29 cells mainly switch from IgM to IgA or IgE [31]. 

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