Limits...
A novel immunoglobulin-immunoglobulin interaction in autoimmunity.

Kawa S, Kitahara K, Hamano H, Ozaki Y, Arakura N, Yoshizawa K, Umemura T, Ota M, Mizoguchi S, Shimozuru Y, Bahram S - PLoS ONE (2008)

Bottom Line: Indeed Western blotting clearly showed that IgG4 binds to IgG1 kappa, IgG2 kappa, IgG3 kappa myeloma proteins, as well as to IgG Fc, in line with a typical RF activity.Further experiments however unraveled the unexpected fact that unlike hitherto known RF, IgG4 does not engage IgG Fc through its Fab, but its very own Fc.In the future, the relevance of NRF, beyond autoimmune pancreatitis, in both diagnosis/prognosis as well as pathophysiology of autoimmune and other systemic diseases where IgG4's role seems paramount, needs to be systematically assessed.

View Article: PubMed Central - PubMed

Affiliation: Center for Health, Safety and Environmental Management, Shinshu University, Matsumoto, Japan. skawapc@hsp.md.shinshu-u.ac.jp

ABSTRACT
Well over six decades since its first description, the Rheumatoid Factor (RF)-autoantibodies recognizing Fc (constant) portion of IgG through their own Fab (antigen binding variable segments)-is believed to have come of age. Autoimmune pancreatitis is a unique form of pancreatitis, biologically characterized by an elevated serum IgG4 concentration. Given the fact that IgG4 myeloma proteins can act as RF, we initially hypothesized that IgG4 in autoimmune pancreatitis might do likewise, hence potentially contributing to disease pathogenesis. Indeed Western blotting clearly showed that IgG4 binds to IgG1 kappa, IgG2 kappa, IgG3 kappa myeloma proteins, as well as to IgG Fc, in line with a typical RF activity. Further experiments however unraveled the unexpected fact that unlike hitherto known RF, IgG4 does not engage IgG Fc through its Fab, but its very own Fc. These data therefore collectively describe a Novel RF (NRF) in autoimmune pancreatitis. In the future, the relevance of NRF, beyond autoimmune pancreatitis, in both diagnosis/prognosis as well as pathophysiology of autoimmune and other systemic diseases where IgG4's role seems paramount, needs to be systematically assessed.

Show MeSH

Related in: MedlinePlus

Reactivity of human IgG4 to various immunoglobulin classes and subclasses.Western blot analysis indicates the reactivity of IgG4 in pooled sera of patients with autoimmune pancreatitis to various human immunoglobulin subclasses. (A) The identity of each commercially-purchased immunoglobulin myeloma protein was confirmed upon reaction with the corresponding HRP-labeled anti-isotype antibodies respectively i.e. IgG1κ, IgG2κ, IgG3κ, IgA1κ, IgA2κ, IgMκ, IgDκ and IgEλ (B) Similarly HRP-labeled antibody against IgG4 Fc specifically reacted to IgG4κ. It also reacted to IgG Fc (faint band on the right panel) but not to IgG Fab or yet Ig Fc lacking IgG4 Fc. (C) An identical membrane (to panel A) was subjected this time, first, to pooled autoimmune pancreatitis sera and then to HRP-labeled anti-IgG4 Fc antibody which in contrast to panel B, reacted to IgG1κ, IgG2κ, IgG3κ, IgG Fc and affinity-purified IgG Fc lacking IgG4 Fc, but not to other human immunoglobulins and IgG Fab, hence establishing the fact that patient IgG4 reacts to IgG1,2 and 3 Fc (additional bands at 220 kDa and about 38 kDa are likely aggregation or degradation products of IgG4). Experiments were repeated three times with identical results and the pooled serum was used at 1∶1000 dilution.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2249926&req=5

pone-0001637-g001: Reactivity of human IgG4 to various immunoglobulin classes and subclasses.Western blot analysis indicates the reactivity of IgG4 in pooled sera of patients with autoimmune pancreatitis to various human immunoglobulin subclasses. (A) The identity of each commercially-purchased immunoglobulin myeloma protein was confirmed upon reaction with the corresponding HRP-labeled anti-isotype antibodies respectively i.e. IgG1κ, IgG2κ, IgG3κ, IgA1κ, IgA2κ, IgMκ, IgDκ and IgEλ (B) Similarly HRP-labeled antibody against IgG4 Fc specifically reacted to IgG4κ. It also reacted to IgG Fc (faint band on the right panel) but not to IgG Fab or yet Ig Fc lacking IgG4 Fc. (C) An identical membrane (to panel A) was subjected this time, first, to pooled autoimmune pancreatitis sera and then to HRP-labeled anti-IgG4 Fc antibody which in contrast to panel B, reacted to IgG1κ, IgG2κ, IgG3κ, IgG Fc and affinity-purified IgG Fc lacking IgG4 Fc, but not to other human immunoglobulins and IgG Fab, hence establishing the fact that patient IgG4 reacts to IgG1,2 and 3 Fc (additional bands at 220 kDa and about 38 kDa are likely aggregation or degradation products of IgG4). Experiments were repeated three times with identical results and the pooled serum was used at 1∶1000 dilution.

Mentions: We first used Western blotting to explore the Ig–Ig interaction patterns of autoimmune pancreatitis patients' IgG4. We initially were able to show that IgG4 was able to bind to human IgG1, IgG2, IgG3 and IgG Fc but not to human IgA, IgM, IgD, IgE and IgG Fab, hence defining it as a de facto RF. In order to do so, we first confirmed the identity of each immunoglobulin myeloma protein used in experiments-IgG1κ, IgG2κ, IgG3κ, IgA1κ, IgA2κ, IgMκ, IgDκ and IgEλ-through reactivity with the corresponding HRP-labeled anti-Ig antibody (Figure 1a). As with other HRP-labeled anti-immunoglobulin antibodies, HRP-labeled anti-IgG4 Fc reacted to IgG4κ myeloma protein and to IgG Fc, but not to IgG Fc lacking IgG4 Fc (Figure 1b). After an identical membrane (as to Figure 1a) was exposed this time first to the pooled sera of autoimmune pancreatitis patients, HRP-labeled anti-IgG4 antibody reacted to IgG1κ, IgG2κ, IgG3κ, IgG Fc, and to a purified IgG Fc lacking IgG4 Fc, but not to other human immunoglobulins or to an IgG F(ab')2 (it should be also noted that the reactivity of HRP-labeled anti-IgG4 antibody to IgG4κ seems to be amplified upon exposure to autoimmune pancreatitis sera). These results hence indicate that IgG4 from autoimmune pancreatitis patients is able to bind IgG1κ, IgG2κ and IgG3κ as well as IgG Fc (and perhaps to IgG4κ myeloma protein itself) (Figure 1c) (it should be noted that several individual sera were equally tested and gave similar results as the pooled serum).


A novel immunoglobulin-immunoglobulin interaction in autoimmunity.

Kawa S, Kitahara K, Hamano H, Ozaki Y, Arakura N, Yoshizawa K, Umemura T, Ota M, Mizoguchi S, Shimozuru Y, Bahram S - PLoS ONE (2008)

Reactivity of human IgG4 to various immunoglobulin classes and subclasses.Western blot analysis indicates the reactivity of IgG4 in pooled sera of patients with autoimmune pancreatitis to various human immunoglobulin subclasses. (A) The identity of each commercially-purchased immunoglobulin myeloma protein was confirmed upon reaction with the corresponding HRP-labeled anti-isotype antibodies respectively i.e. IgG1κ, IgG2κ, IgG3κ, IgA1κ, IgA2κ, IgMκ, IgDκ and IgEλ (B) Similarly HRP-labeled antibody against IgG4 Fc specifically reacted to IgG4κ. It also reacted to IgG Fc (faint band on the right panel) but not to IgG Fab or yet Ig Fc lacking IgG4 Fc. (C) An identical membrane (to panel A) was subjected this time, first, to pooled autoimmune pancreatitis sera and then to HRP-labeled anti-IgG4 Fc antibody which in contrast to panel B, reacted to IgG1κ, IgG2κ, IgG3κ, IgG Fc and affinity-purified IgG Fc lacking IgG4 Fc, but not to other human immunoglobulins and IgG Fab, hence establishing the fact that patient IgG4 reacts to IgG1,2 and 3 Fc (additional bands at 220 kDa and about 38 kDa are likely aggregation or degradation products of IgG4). Experiments were repeated three times with identical results and the pooled serum was used at 1∶1000 dilution.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2249926&req=5

pone-0001637-g001: Reactivity of human IgG4 to various immunoglobulin classes and subclasses.Western blot analysis indicates the reactivity of IgG4 in pooled sera of patients with autoimmune pancreatitis to various human immunoglobulin subclasses. (A) The identity of each commercially-purchased immunoglobulin myeloma protein was confirmed upon reaction with the corresponding HRP-labeled anti-isotype antibodies respectively i.e. IgG1κ, IgG2κ, IgG3κ, IgA1κ, IgA2κ, IgMκ, IgDκ and IgEλ (B) Similarly HRP-labeled antibody against IgG4 Fc specifically reacted to IgG4κ. It also reacted to IgG Fc (faint band on the right panel) but not to IgG Fab or yet Ig Fc lacking IgG4 Fc. (C) An identical membrane (to panel A) was subjected this time, first, to pooled autoimmune pancreatitis sera and then to HRP-labeled anti-IgG4 Fc antibody which in contrast to panel B, reacted to IgG1κ, IgG2κ, IgG3κ, IgG Fc and affinity-purified IgG Fc lacking IgG4 Fc, but not to other human immunoglobulins and IgG Fab, hence establishing the fact that patient IgG4 reacts to IgG1,2 and 3 Fc (additional bands at 220 kDa and about 38 kDa are likely aggregation or degradation products of IgG4). Experiments were repeated three times with identical results and the pooled serum was used at 1∶1000 dilution.
Mentions: We first used Western blotting to explore the Ig–Ig interaction patterns of autoimmune pancreatitis patients' IgG4. We initially were able to show that IgG4 was able to bind to human IgG1, IgG2, IgG3 and IgG Fc but not to human IgA, IgM, IgD, IgE and IgG Fab, hence defining it as a de facto RF. In order to do so, we first confirmed the identity of each immunoglobulin myeloma protein used in experiments-IgG1κ, IgG2κ, IgG3κ, IgA1κ, IgA2κ, IgMκ, IgDκ and IgEλ-through reactivity with the corresponding HRP-labeled anti-Ig antibody (Figure 1a). As with other HRP-labeled anti-immunoglobulin antibodies, HRP-labeled anti-IgG4 Fc reacted to IgG4κ myeloma protein and to IgG Fc, but not to IgG Fc lacking IgG4 Fc (Figure 1b). After an identical membrane (as to Figure 1a) was exposed this time first to the pooled sera of autoimmune pancreatitis patients, HRP-labeled anti-IgG4 antibody reacted to IgG1κ, IgG2κ, IgG3κ, IgG Fc, and to a purified IgG Fc lacking IgG4 Fc, but not to other human immunoglobulins or to an IgG F(ab')2 (it should be also noted that the reactivity of HRP-labeled anti-IgG4 antibody to IgG4κ seems to be amplified upon exposure to autoimmune pancreatitis sera). These results hence indicate that IgG4 from autoimmune pancreatitis patients is able to bind IgG1κ, IgG2κ and IgG3κ as well as IgG Fc (and perhaps to IgG4κ myeloma protein itself) (Figure 1c) (it should be noted that several individual sera were equally tested and gave similar results as the pooled serum).

Bottom Line: Indeed Western blotting clearly showed that IgG4 binds to IgG1 kappa, IgG2 kappa, IgG3 kappa myeloma proteins, as well as to IgG Fc, in line with a typical RF activity.Further experiments however unraveled the unexpected fact that unlike hitherto known RF, IgG4 does not engage IgG Fc through its Fab, but its very own Fc.In the future, the relevance of NRF, beyond autoimmune pancreatitis, in both diagnosis/prognosis as well as pathophysiology of autoimmune and other systemic diseases where IgG4's role seems paramount, needs to be systematically assessed.

View Article: PubMed Central - PubMed

Affiliation: Center for Health, Safety and Environmental Management, Shinshu University, Matsumoto, Japan. skawapc@hsp.md.shinshu-u.ac.jp

ABSTRACT
Well over six decades since its first description, the Rheumatoid Factor (RF)-autoantibodies recognizing Fc (constant) portion of IgG through their own Fab (antigen binding variable segments)-is believed to have come of age. Autoimmune pancreatitis is a unique form of pancreatitis, biologically characterized by an elevated serum IgG4 concentration. Given the fact that IgG4 myeloma proteins can act as RF, we initially hypothesized that IgG4 in autoimmune pancreatitis might do likewise, hence potentially contributing to disease pathogenesis. Indeed Western blotting clearly showed that IgG4 binds to IgG1 kappa, IgG2 kappa, IgG3 kappa myeloma proteins, as well as to IgG Fc, in line with a typical RF activity. Further experiments however unraveled the unexpected fact that unlike hitherto known RF, IgG4 does not engage IgG Fc through its Fab, but its very own Fc. These data therefore collectively describe a Novel RF (NRF) in autoimmune pancreatitis. In the future, the relevance of NRF, beyond autoimmune pancreatitis, in both diagnosis/prognosis as well as pathophysiology of autoimmune and other systemic diseases where IgG4's role seems paramount, needs to be systematically assessed.

Show MeSH
Related in: MedlinePlus