Abstract
Objective: To determine whether the anti-GM1 antibody IgG subclass (IgG1 to 4) is associated with clinical profiles and patterns of recovery in Guillain–Barré syndrome (GBS).
Methods: The IgG subclassification of anti-GM1 antibody was examined and compared with clinical data on 42 GBS patients positive for the antibody.
Results: Frequent anti-GM1 antibody subclasses were IgG1 (76%) and IgG3 (31%). IgG1 antibody was associated with preceding gastroenteritis and Campylobacter jejuni serology, whereas IgG3 antibody was associated with preceding respiratory infection. Although the severity at nadir was similar for IgG1- and IgG3-positive patients, the percentage of patients who could not walk independently was greater for the IgG1-positive group 1 month (42 vs 0%; p = 0.02), 3 months (28 vs 0%), and 6 months (25 vs 0%) after onset. Rapid recovery within 1 month occurred frequently in the patients with the IgG3 antibody but rarely in those with the IgG1 antibody (67 vs 11%; p = 0.003).
Conclusions: The IgG1 subclass of anti-GM1 antibody is a major subtype indicative of slow recovery, whereas isolated elevation of IgG3 subclass antibody titer suggests rapid recovery. Variation in subclass patterns may depend on which pathogen precipitates GBS.
Guillain–Barré syndrome (GBS) is a self-limited, autoimmune-mediated neuropathy. Muscle weakness usually reaches its nadir within 2 to 3 weeks, partial or complete recovery occurring over weeks to months. Patients with anti-GM1 IgG autoantibody constitute a subgroup of GBS that has the uniform features of antecedent Campylobacter jejuni infection, pure motor neuropathy, and electrophysiologic evidence of primary axonal dysfunction.1-3⇓⇓ Our previous study found that there were two patterns of clinical recovery in patients with anti-GM1 IgG antibody: faster or slower recovery than those without the antibody.4 Although patients with anti-GM1 IgG antibody more often show poor outcome, probably because of extensive axonal degeneration, some patients show markedly rapid recovery during the first 4 weeks. Which factors predict the speed of recovery and outcomes, however, have yet to be clarified.
There are four subclasses of human IgG, IgG1 to 4, which differ in both their structural and biologic properties. Several autoimmune diseases show a skewed increase in IgG subclass autoantibodies.5-7⇓⇓ Furthermore, determination of the IgG subclass of some autoantibodies is reported to be important in understanding clinical features.8-11⇓⇓⇓ In GBS, the main anti-ganglioside antibodies are IgG1 and IgG3.12-16⇓⇓⇓⇓ In Fisher syndrome, a clinical variant of GBS, the IgG subclass of anti-GQ1b antibody and prior infection are closely associated, IgG3 being the main subclass in patients with Fisher syndrome after respiratory infection and IgG2 in patients with preceding gastrointestinal infection.17 In GBS, however, it is not clear whether the IgG subclassification of anti-GM1 antibody is related to clinical features. We therefore examined the IgG subclassification of anti-GM1 antibodies in patients with GBS to determine whether a particular IgG subclass is associated with clinical profiles, particularly patterns of clinical recovery and outcomes.
Methods.
Patients.
Of 134 consecutive GBS patients seen at Chiba University Hospital or its affiliated hospitals between 1989 and 2001, 42 (31%) had serum anti-GM1 IgG antibody. They fulfilled the clinical criteria for GBS.18 Their disabilities were evaluated by the Hughes functional grading scale (grade 1: minimal symptoms and signs, able to run; grade 2: able to walk 5 meters independently; grade 3: able to walk 5 meters with aid; grade 4: chair or bed bound; grade 5: requires assisted ventilation). Patients were followed up for 6 months after onset.
Serologic assays.
Serum samples taken during the first 3 weeks after onset, before immune treatment, were frozen and stored at −80 °C until used. An ELISA, done as reported elsewhere,19 was used to measure serum IgG antibodies to GM1, GM1b, GM2, GD1a, GalNAc-GD1a, GD1b, GT1b, and GQ1b but with peroxidase-conjugated anti-human γ-chain-specific antibody (Dako, Glostrup, Denmark) at the dilution of 1:4,000 (1:1,000 in our other studies) as the secondary antibody. This dilution rate corresponded to activities of the secondary antibodies in the IgG subclass-determinant assay, as reported below. Anti-ganglioside antibody titer was the highest serum dilution that gave an optical density of ≥0.1 at 492 nm. Serum was considered positive for anti-ganglioside antibodies when the titer was ≥500. Evidence of recent infection by C. jejuni or Haemophilus influenzae was assayed serologically as reported elsewhere.20,21⇓
Determination of anti-ganglioside antibody IgG subclasses.
IgG subclasses of anti-ganglioside antibodies were examined in an ELISA done with peroxidase-conjugated mouse anti-human γ1, γ2, γ3, and γ4 chain-specific monoclonal antibodies (Southern Biotechnology Associates, Birmingham, AL) as the secondary antibodies. These antibodies were used at various dilutions (γ1 at 1:250, γ2 at 1:500, γ3 and γ4 at 1:8,000), which give similar optical density values for equal quantities of purified human myeloma plasma protein of different IgG subclasses (Athens Research and Technology, Athens, GA).
Statistical analysis.
Differences in percentages were examined by the χ2 or Fisher’s exact test. Differences in medians were examined by the Mann–Whitney U test. A difference was considered significant when the p value was <0.05. All statistical analyses were done with Statcel software (OMS, Saitama, Japan).
Results.
IgG subclassification.
Of the 42 anti-GM1-positive patients, 32 (76%) had the IgG1 and 13 (31%) had the IgG3 antibodies, whereas none had the IgG4 antibody. Two (5%) patients had the IgG2 antibody: One had isolated elevation of IgG2 antibody activity and one low IgG2 antibody activity together with high IgG1 antibody activity. The most frequent subclass pattern was isolated elevation of IgG1 antibody (64%) and the second isolated elevation of IgG3 antibody (21%), whereas these antibodies coexisted in only four patients (10%). Those with anti-GM1 IgG antibody often had IgG antibodies against other gangliosides, and the IgG subclass patterns of the other anti-ganglioside antibodies were almost the same as the subclass pattern of anti-GM1 antibody in individual cases.
Clinical characteristics and anti-GM1 antibody IgG subclass.
The IgG subclassification of anti-GM1 antibody was closely associated with antecedent infectious symptoms (table). Patients with the IgG1 antibody frequently had a history of gastrointestinal infectious symptoms and positive serology for recent C. jejuni infection. In contrast, preceding upper respiratory tract infection was common in patients with the IgG3 antibody. There was no association of the IgG subclass with age, sex, anti-GM1 IgG antibody titer, compound muscle action potential amplitude after median nerve stimulation at the wrist during the acute phase of illness, or H. influenzae serology. Patients with the IgG1 or IgG3 antibody received similar treatment.
Table Anti-GM1 antibody IgG subclass association with clinical features
Correlation of IgG subclass with severity and functional outcome.
The patients (n = 4) who had both IgG1 and IgG3 antibodies were excluded from subsequent analysis to simply compare the outcome between the IgG1- and the IgG3-positive patients. At the peak of the disease, there was no significant difference in Hughes grades between the IgG1 and IgG3 antibody–positive patients (median grade 3 [range 1 to 5] vs 4 [1 to 4]). One month after onset, however, the median Hughes grade was higher for patients who had the IgG1 antibody (median grade 3 [range 0 to 5] vs 1 [1 to 2]; p = 0.02). The percentage of patients who could not walk independently was greater in the IgG1 antibody–positive than the IgG3-positive group (42 vs 0%; p = 0.02) (figure 1). Three and 6 months after onset, a grade of ≥3 disability remained, respectively, 28% (7/25) and 25% (6/24) for patients with the IgG1 antibody, whereas by 1 month after onset, all patients (n = 9) with the IgG3 antibody had a grade of ≤2.
Of the 42 patients who were anti-GM1-positive, 21 received plasmapheresis and 9 IV immunoglobulin (IVIg). In the plasmapheresis-treated group, most patients who had the IgG1 antibody had slow recoveries, and 50% had disabilities of a Hughes grade of ≥3 even 6 months after onset. In contrast, all nine patients treated with IVIg had a Hughes grade of ≤2 at 3 months after onset, irrespective of their anti-GM1 antibody subclassification.
Rapid recovery.
Rapid recovery, which was defined as improvement of two or more Hughes grades from the peak by 1 month after onset, was more frequent in the IgG3 antibody–positive than the IgG1 antibody–positive groups (67 vs 11%; p = 0.003). In the IgG3 antibody–positive group, all six patients who showed rapid recovery received plasmapheresis (n = 4) or IVIg (n = 2), whereas all three patients who did not show rapid recovery received neither of them. In the IgG1 antibody-positive group, three of five patients treated with IVIg showed rapid recovery, whereas none of 22 patients treated with plasmapheresis (n = 14) or conservative therapies (n = 8) showed (60 vs 0%; p = 0.003).
Analysis of anti-GM1 IgG antibody activity on serial sampling.
Longitudinal change of anti-GM1 IgG activity was investigated to examine whether serum half-life is different between the IgG1 and IgG3 antibodies. Because serial samples were not available from the patients in this study, anti-GM1 IgG-positive samples in our serum bank were used. Decreasing rate of the antibody activity did not differ apparently between the IgG1 and IgG3 antibody–positive patients (figure 2, A and B).
Discussion.
Our study shows that IgG1 is the most frequent subclass of anti-GM1 antibody in GBS and is associated with preceding C. jejuni infection and slow recovery. Anti-GM1 IgG1 antibody therefore can serve as a predictor of delayed recovery by GBS patients. In contrast, our findings suggest that isolated elevation of the IgG3 subclass of anti-GM1 antibody is related to preceding respiratory illness, rapid recovery, and good outcome. There was no difference between IgG subclasses in severity at nadir. The outcome could be influenced by various treatment modes the patients had received. We, however, concluded that at least in plasmapheresis-treated patients, IgG subclassification of anti-GM1 antibody is closely associated with outcome because the frequency of plasmapheresis treatment did not differ between the patients with the IgG1 and IgG3 antibodies, as shown in the table.
Several features that indicate a poor outcome for GBS have been identified: old age, preceding gastrointestinal illness (C. jejuni infection), recent cytomegalovirus infection, severe muscle weakness at nadir, a short period to becoming bed bound, ventilation required, and low or absent compound muscle action potential amplitudes.22,23⇓ Preserved tendon reflexes, preceding H. influenzae infection, as well as IVIg treatment were predictors of rapid clinical recovery.24 We found that the anti-GM1 antibody IgG subclassification is related to C. jejuni serology but not to age, disability scale at nadir, compound muscle action potential amplitudes, or H. influenzae serology. Because serologic assays for C. jejuni infection often give false-positive or -negative results, we concluded that the IgG subclassification of anti-GM1 antibody is useful for predicting outcome in GBS. Furthermore, IgG subclass patterns of the other anti-ganglioside antibodies were the same as the subclass pattern of anti-GM1 antibody in individual cases, indicating that the subclass profiles of antibodies against gangliosides other than GM1 also may serve as predictors for types of recovery.
The different biological properties of the IgG subclasses may account for the close association between IgG1/IgG3 antibodies and the type of clinical recovery. First, IgG3 has a much shorter serum half-life than the other subclasses (8 vs 23 days). We, however, failed to find any difference in the anti-GM1 decrease rate in patients with the IgG1 or IgG3 antibody. Second, human IgG1 is the most effective subclass in the mediation of antibody-dependent cell-mediated cytotoxicity.25 Pathologic studies of autopsy cases of acute motor axonal neuropathy (AMAN) showed IgG and complement activation product deposition in the axolemma of motor fibers, indicating that AMAN is an antibody- and complement-mediated disorder.26,27⇓ We suggest that the greater potency of anti-GM1 IgG1 antibody in mediating antibody-dependent cell-mediated cytotoxicity contributes to slow clinical recovery in GBS. Third, there is a difference in antibody affinity for GM1 ganglioside. A previous study found that patients with a high-affinity anti-GM1 IgG antibody were likely to have axonal involvement, but there was no correlation between the affinity of anti-GM1 IgG antibody and the IgG subclass.28 The possibility cannot be excluded that the characteristic IgG subclass profiles may reflect levels of other factors, including cytokines, which are affected by the type of antecedent infection29 and which actually define the type of recovery from GBS.
Figure 1. Percentage of patients with a Hughes grade of ≥3. Patients had IgG1 or IgG3 anti-GM1 antibody. Patients with the IgG1 antibody often have severe residual disabilities, but patients with the IgG3 antibody rarely. *p = 0.02. = IgG1 Ab (+); = IgG3 Ab (+).
Figure 2. Longitudinal change of anti-GM1 IgG activity. (A) shows the anti-GM1 IgG antibody activities in patients (n = 5; ▪) with the IgG1 but without IgG3 antibody. (B) shows those in patients (n = 4; ▴) with the IgG3 but without IgG1 antibody. Note that all patients with the IgG3 antibody as well as some with the IgG1 antibody had higher anti-GM1 IgG activity than cutoff value (optical density 0.1) even 5 weeks after the onset of the disease.
It is noteworthy that all the patients treated with IVIg had good recoveries, irrespective of the anti-GM1 antibody IgG subclassification. Previous findings suggest that IVIg is more effective than plasmapheresis for patients with anti-GM1 (IgG) antibody.2,4⇓ This tendency seems to depend on the superior efficacy of IVIg for those patients who have the IgG1 subclass antibody.
Our study confirms the previous findings that the anti-GM1 IgG antibody present is mainly IgG1 or IgG3.12-16⇓⇓⇓⇓ We also found that the IgG1 subclass antibody was associated with preceding C. jejuni enteritis, which is compatible with previous reports of the detection of IgG1 antibody in all cases in which there was C. jejuni serology.15,28⇓ Notably, our study showed that several patients had only the IgG3 antibody, and they often had had a preceding upper respiratory infectious illness, but the causative agents that induce anti-ganglioside IgG3 antibodies were not identified. In Fisher syndrome, anti-GQ1b IgG antibody is skewed toward the IgG3 subclass in patients who have had a respiratory infectious illness.17 Our findings suggest that the IgG subclass pattern reflects the immune response elicited by the particular pathogen that precipitates the disease, even though IgG subclass responses against some bacteria are partly affected by the host’s genetic factors.30 Identification of IgG3 antibody-inducing agents may be helpful to clarify the mechanism of rapid recovery frequently seen in GBS patients with anti-GM1 IgG3 antibody.
Acknowledgments
Supported in part by grants in aid from the Uehara Memorial Foundation, grants in aid for Scientific Research (B) (KAKENHI 14370210 to N.Y.) from the Ministry of Education, Culture, Sports, Science, and Technology of Japan, and a Research Grant for Neuroimmunological Diseases from the Ministry of Health, Labour, and Welfare of Japan. M.K. is a research fellow (no. 4734) of the Japan Society for the Promotion of Science.
Acknowledgment
The authors thank Ms. Y. Tsuchiya and Ms. M. Okazaki (Dokkyo University, Tochigi) for their technical assistance in testing the anti-ganglioside antibody.
- Received August 23, 2002.
- Accepted January 27, 2003.
References
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