LO-MG SYnAbs rat-anti IgG mouse monoclonals


Our customers are starting to understand how we work but new ones don't necessarily find their way around all the SYnAbs nomenclatures. So today let's take a look at just one of our most popular references: LO-MG.


SYnAbs off-the-shelf monoclonals catalog focuses mainly on secondary antibodies. Developed from our proprietary rat species, the rat-LOU, all references beginning with the letters LO, are monoclonal antibodies whose host species is the rat-LOU.


The following letters refer first to the species, and then to the targeted antigen. In this case, the M in LO-MG refers to the mouse species, and the letter G to the IgG isotype. The numbers that follow refer to the isotype subclasses.



·      LO-MG-1 is a rat antibody specifically targeting mouse IgG1,

·      LO-MG2a is a rat antibody specifically targeting mouse IgG2a,

·      LO-MG2b is a rat antibody specifically targeting mouse IgG2b,

·      LO-MG3 is a rat antibody specifically targeting mouse IgG3,


without cross-reacting with other subclasses or isotypes.


LO-MGCOC is the COCktail of the previously described kappa rat monoclonals targeting anti-mouse IgG1, IgG2a, IgG2b and IgG3 heavy chain.


Are you still following me?


Let's now take a closer look at what these tools can be used for.


LO-MG : rat anti-mouse IgG monoclonal antibodies to monitore immune isotypic response to infectious diseases


The isotype of an antibody determines its Fc-dependent effector functions and is of vital importance in determining an appropriate route of immune clearance for specific pathogens.


In 1992, Pascal Pierre et al (1) were studying cholera toxin. While the immunoadjuvant effect of cholera toxin was clearly accepted at that time, the effect of the B subunit of cholera toxin was still rather controversial. In addition, as the cellular mechanisms of cholera toxin adjuvanticity were poorly understood, they decided to investigate the in vivo effect of cholera toxin and B subunit of cholera toxin on IgG subclass responses in mouse species.


Since the experiments were conducted at UCL in the department of Hervé Bazin, which later gave birth to SYnAbs, the necessary tools for the investigation were at hand: rat mAb against mouse IgGl (LO-MG1-2), rat mAb against mouse IgG2a (LO-MG2a-3), rat mAb against mouse IgG2b (LO-MG2b-2), rat mAb against mouse IgG3 (LO-MG3-7), and finally rat mAb against mouse IgE (LO-ME-3).


Results confirmed the ability of cholera toxin to abrogate oral tolerance induced by feeding OVA. B subunit of cholera toxin mixed with OVA, without coupling, primed the immune system, but the IgG anti-OVA response after boosting was not statistically different from that observed by feeding PBS or OVA separately before OVA boosting.


In 1994, el Bouhdidi et al (2) notes that the scientific community has only incomplete information on the circulating Ig during the incubation period of Chagas disease in humans. Chagas disease is a parasitic disease found in tropical regions of South America. It is of animal origin and transmissible to humans by triatomine insects living in the burrows of wild animals and in human dwellings. Identified in 1909 in Brazil by Dr. Carlos Chagas (1879-1934), the protozoan Trypanosoma cruzi is the cause of Chagas disease.


To monitor and identify isotypic response in experimental T. cruzi infection in mice, El Bouhdidi et al has so ordered from SYnAbs rat monoclonal antibody anti-mouse IgA and IgE chains (respectively LO-MA-8 and LO-ME-3), but also rat specific for mouse Ig heavy chains i.e. LOMG-1-2, LO-MG2a-2, LO-MG-2b-2 and LOMG3-7.


They demonstrated :

  • mouse IgG2a concentrations were two to 67 times higher than that of the other IgG, IgA or IgM antibody isotypes,
  • there’s a persistence of high IgM antibody titres
  • the occurrence of IgE and IgA antibody responses, not previously reported in T. cruzi experimental infection.


LO-MG: rat anti-mouse IgG monoclonal antibodies to monitore immunomostimulatory properties of vaccine candidates


Toxoplasmosis is a disease caused by infection with a parasite (Toxoplasma gondii). It is usually transmitted to humans by domestic animals, especially cats, or by eating undercooked meat. The disease can be dangerous for people with weakened immune systems (HIV-infected…) or for pregnant women.


Echeverria et al (3) decided to try to elicit a humoral and cellular response in mice thus proving the concept of a new type of vaccine based upon the injection of Leishmania infantum Heat shock proteins 83, or LiHsp83.


The adjuvant and immunoprotective value of such trial was monitored thanks to SYnAbs rat anti-mouse IgG1 heavy chain (LO-MG1-2) and rat anti-mouse IgG2a heavy chain (LO-MG2a-9) in ELISA plates.


Study demonstrated that the member of heat shock protein 90 family, LiHsp83, was a good candidate to carry antigens and develop an adjuvant-free vaccine to generate the adequate Th1 immune response to Toxoplasma gondii.


LO-MG: rat anti-mouse IgG monoclonal antibodies to comprehend B-cells & T-cells interactions and potential triggers


In 1993, although it was well established that B-lymphocytes were able to present antigen in vitro, the ability of small resting B cells to do the same in vivo was controversial. Olivier Denis et al (4) decided to investigate the potential of resting B cells to act as antigen presenting cells.


To determine the ability of B cells to act as APCs in vivo, BALB/c mice were immunized with DNP coupled IR-418 (isotype control rat monoclonal lgG2a), LO-MM-9 (IgG2a kappa rat anti-mouse mu heavy chain) and LO-MD-6 (IgG2a kappa rat anti-mouse delta heavy chain). Levels of anti-rat Ig specific antibodies were determined using LO-MG1-13, LO-MG1-2, LO-MG2a-3, LO-MG2b-2, and LO-MG3-13. The team concluded that resting B cells could present antigen to T cells and efficiently induce an antibody response in vivo. Furthermore, the absence of specific lgG2a secretion strongly suggested that B cells, and not dendritic cells, are the in vivo APCs that induce a specific antibody response.


In 1995, Marcelle Van Mechelen et al (5) wondered if B cell tolerance and Th1 unresponsiveness were functionally related when mice were injected with high doses of monomeric human gamma globulins. They hypothesized that the failure to induce Th1 cells resulted from antigen presentation to naive T cells by co-stimulatory-deficient, resting B cells and/or B cells that were rendered tolerant to the antigen.


Serum levels of antigen-specific antibodies were determined by ELISA according to standard procedures using SYnAbs rat mAbs specific for murine lgG1 (LO-MG1-13) and lgG2a (LO-MG2a-7). For the determination of specific IgE responses, SYnAbs mAb LO-ME-3 was used as capture antibody.


They concluded that while B cell tolerance was only observed in response to deaggregated antigen, injection of all forms of protein antigens induces T helper precursor cells to differentiate into Th2-type helper cells in vivo independently of the B cell tolerance status.


LO-MG: rat anti-mouse IgG monoclonal antibodies to understand pathology-related mechanisms in transgenic mouse models


DREAM or KCNIP3 is a human transmembrane protein ion channel, - referred as “potassium voltage-gated channel interacting protein 3” -  highly expressed in immune cells. Working on the mechanisms of this voltage-gated potassium (Kv) channel-interacting protein, Savignac et al. (6) set up transgenic mice for DREAM.


The team decided to monitore Ig synthesis and B-cells proliferation thanks to SYnAbs rat anti-mouse IgG1 (LO-MG1-13), IgG2a (LO-MG2a-9), IgG2b (LO-MG2b-1), IgG3 (LO-MG3-13), IgM (LO-MM-3), IgE (LO-ME-3) for coating and rat anti-mouse (LO-MK-1) as secondary detection step. Results disclosed a novel function of DREAM in proliferation and Ig synthesis in B-lymphocytes.


Similarly, in the mucosal model 12/15-LO knockout mouse, Hajek et al (7) wanted to measure circulating levels of allergen-specific IgE, IgG1, and IgG2a thanks to SYnAbs secondary monoclonals. They concluded that induction of 15-LO-1 in asthma might contribute to allergic sensitization and airways inflammation, potentially by causing suppression of secretory IgA.




(1)  Pierre, P., Denis, O., Bazin, H., Mbella, E. M., & Vaerman, J.-P. (1992). Modulation of oral tolerance to ovalbumin by cholera toxin and its B subunit. European Journal of Immunology, 22(12), 3179–3182. doi:10.1002/eji.1830221223


(2)  El Bouhdidi A, Truyens C, Rivera MT, Bazin H, Carlier Y. Trypanosoma cruzi infection in mice induces a polyisotypic hypergammaglobulinaemia and parasite-specific response involving high IgG2a concentrations and highly avid IgG1 antibodies. Parasite Immunol. 1994 Feb;16(2):69-76. doi: 10.1111/j.1365-3024.1994.tb00325.x. PMID: 8015857.


(3)  Echeverria PC, de Miguel N, Costas M, Angel SO. Potent antigen-specific immunity to Toxoplasma gondii in adjuvant-free vaccination system using Rop2-Leishmania infantum Hsp83 fusion protein. Vaccine. 2006 May 8;24(19):4102-10. doi: 10.1016/j.vaccine.2006.02.039. Epub 2006 Mar 3. PMID: 16545504.


(4)  Denis, O., Latinne, D., Nisol, F., & Bazin, H. (1993). Resting B cells can act as antigen presenting cells in vivo andinduce antibody responses. International Immunology, 5(1), 71–78. doi:10.1093/intimm/5.1.71


(5)  Van Mechelen, M., De Wit, D., Ryelandt, M., Hjulstrōm, S., Heynderickx, M., Bazin, H., … Leo, O. (1995). Induction of Th2 responses to soluble proteins is independent of B cell tolerance status. International Immunology, 7(2), 199–205. doi:10.1093/intimm/7.2.199 


(6)  Savignac M, Mellström B, Bébin AG, Oliveros JC, Delpy L, Pinaud E, Naranjo JR. Increased B cell proliferation and reduced Ig production in DREAM transgenic mice. J Immunol. 2010 Dec 15;185(12):7527-36. doi: 10.4049/jimmunol.1000152. Epub 2010 Nov 8. PMID: 21059893.


(7)  Hajek AR, Lindley AR, Favoreto S Jr, Carter R, Schleimer RP, Kuperman DA. 12/15-Lipoxygenase deficiency protects mice from allergic airways inflammation and increases secretory IgA levels. J Allergy Clin Immunol. 2008 Sep;122(3):633-9.e3. doi: 10.1016/j.jaci.2008.06.021. Epub 2008 Aug 9. PMID: 18692885; PMCID: PMC2802267.