Canine Mast Cell Activation via Human IgG1 and IgG4

Abstract

Background: We have reported that canine mastocytoma-derived CM-MC cells are activated via canine IgG and express a high-affinity IgG receptor (canine FcγRI). The predicted amino acid sequence of the canine FcγRI α subunit was found to be 72% similar to that of humans. These results suggest that canine FcγRI have binding activity with human IgG and led us to investigate CM-MC activation via canine FcγRI and human IgG. Methods: The binding of human IgG to canine FcγRI was examined by flow cytometry using FITC-conjugated human IgG. [Ca²⁺]i increase or histamine release via canine FcγRI and the four human IgG subclasses was measured following aggregation of IgG-bound FcγRIs by anti-human IgG. To determine the binding activity of canine FcγRI with human IgG1 or IgG3, the displacement of ¹²⁵I-labeled canine IgG from canine FcγRI was examined by unlabeled human IgG1 or IgG3. Results: The fluorescence intensity of CM-MC cells was markedly (about 50 times) elevated by incubation with FITC-human IgG compared with the fluorescence of the control cells. A significant (p < 0.01) calcium response and histamine release were observed following aggregation of canine FcγRIs bound with human IgG1 or IgG4. ¹²⁵I-labeled canine IgG was displaced from canine FcγRI by preincubation with unlabeled total human IgG or human IgG1 dose-dependently, whereas no displacement was detected by preincubation with human IgG3. Conclusions: Canine FcγRI possesses a significant binding activity with human IgG1 or IgG4, while IgG2 or IgG3 did not significantly react with canine FcγRI on CM-MC cells.

IgE and IgG antibodies in skin allergy of the horse

“…In humans and rodents, IgG antibodies can also bind to various IgG receptors (FcγRs) on mast cells and activate or inhibit degranulation depending on the receptor [7,21,22]. IgG binding to canine mast cells via Fcγ-receptors has also been reported [23]. In our experiments using six healthy horses, an immediate skin reaction was induced in all horses by anti-IgE134 and in five out of six horses by the anti-IgG(T) antibody CVS40.…”

Identification of Allergens in the Box Jellyfish <b><i>Chironex yamaguchii</i></b> That Cause Sting Dermatitis

“…Taken together, it was shown that CqTX-A caused a mixed venom immune reaction, although the precise mechanisms remain unknown. In particular, it is not known whether IgG (IgG 4 ) is involved in the late-phase reaction or if it reflects the repeated sting injury [24,25]. IgG 1 has been found to be involved in systemic anaphylaxis in a mouse model [26] and in the late asthmatic response in an epidemiological survey [27].…”

“…IgG 1 has been found to be involved in systemic anaphylaxis in a mouse model [26] and in the late asthmatic response in an epidemiological survey [27]. It has also been recognized in canine mast cell activations [25]. The pathogenesis caused by the venom from wasp and bee stings and that of aspergillosis or anisakis disease cannot be explained by allergic or toxic reactions alone.…”

Generation and characterization of novel canine malignant mast cell line CL1

“…The BR cells have been used to examine the ability of malignant mast cells to respond to various chemicals (Garcia et al, 1998), while the CM-MC cells have been used to demonstrate that mast cells can degranulate upon cross-linking of human IgG1 or IgG4 bound to the low-affinity IgG receptor (Sato et al, 2004). Both the C2 and BR cells possess KIT mutations in the juxtamembrane domain that cause constitutive activation, and as such these lines have been used to explore the use of targeted therapeutics directed at KIT inhibition (Liao et al, 2002; London et al, 1999; Ma et al, 1999).…”