Heikki Sarvas

The Four Subclasses of IgG Can Be Isolated from Mouse Serum by using Protein A-Sepharose

We confirmed the findings of Ey and colleagues that mouse IgG is absorbed by protein A‐Sepharose at pH 8.0. Also confirmed was their finding that IgG1 mainly elutes from such a column by means of a buffer with pH 6.0 and that the corresponding pH values for IgG2a and IgG2b were 4.5 and 3.5. We made the new finding that the hulk of IgG2a bearing allotypes a or j eluted already at pH 5, in contrast to IgG2a bearing allotype b. Another newfinding was that IgG3 was mainly eluted at pH 4.5 regardless of the allotype. All four subclasses of IgG could thus be physically separated if the allotype was a or J (the only known exception is allotype b). Separation of IgG2a and IgG3 was achieved even when the allotype was b by using a pH gradient for elution. IgG2a came out al a slightly higher pH than IgG3. Mouse IgG antibodies against group A streptococcal polysaccharide belonged mostly to IgG3 and, to a lesser extent, to IgG2a and IgG2b.

IgG subclasses of pneumococcal antibodies ― Effect of allotype G2m(n)

Antibody responses to three pneumococcal polysaccharides (types 3, 14, and 18C) were analysed after vaccination with a 23‐valent polysaccharide vaccine. Antibodies to all three polysaccharides could be detected before immunization. Clear cut IgG, IgA, and/or IgM antibody responses to the polysaccharides were seen in three‐quarters of the vaccines IgG2 was the predominant and IgG1 the second most abundant subclass of anti‐pneumococcal IgG antibodies both before and after the vaccination. The relative proportions of IgG2 and IgG1 antibodies exhibited a continuous variation from 1:0 to approximately 0:2. After vaccination. G2m(n)‐positive homozygotes had about four times more IgG2 antibodies (anti‐14 und anti‐18C than G2m(n)‐negative vaccinees. Heterozygotes occupied an intermediate position. The same pattern was seen less clearly in type 3 antibodies after vaccination, and in all three antibodies before vaccination. The G2m(n) allotypes had no detectable effect on the levels of IgG1, IgG4, or IgM antibodies, and possibly a weak effect on IgG3 and IgA antibodies (G2m(n)‐positive homozygotes responded strongly).

Half-life of the maternal IgG1 allotype in infants

The residence time of maternal IgG1 in the circulation of infants was measured by monitoring f-allotypic IgG1 or f-positive tetanus toxoid antibody in geneticallyG1mf-negative infants.G1ma-positive maternal tetanus toxoid antibody was similarly monitored in genetically a-negative infants. Blood samples were taken from infants at the age of 1–3 days, ca. 4 months, and ca. 6 months. An exponential decay at the same rate took place from age 1–3 days to 4 months and for the 2 subsequent months. The average concentration of the maternal IgG1 had dropped to ca. 10% of the 1- to 3-day value in 4 months and to ca. 3% in 6 months. The drop was due mainly to clearance but partly also to the weight increase of the child (doubling in 6 months). By correcting for the weight increase, we calculated that ca. 17 and 7% of the original maternal IgG1 was still present at ages 4 and 6 months, respectively. The average half-life of the maternal IgG1 was thus 48.4 days. The concentration of endogenous IgG1 in the cord blood was determined by studying a separate series of mother-newborn pairs. Assuming that cross-reactions of antiallotype reagents had no effect, the highest measured concentration of f-positive IgG1 in infants of f-negative mothers was 10 mg/L, half a percent of adult heterozygote values. Crossreaction may have played a role, however, and the value must be considered the upper limit of the true concentration.

Subtly Impaired Humoral Immunity Predisposes to Frequently Recurring Genital Herpes Simplex Virus Type 2 Infection and Herpetic Neuralgia

BACKGROUND Immunogenetic factors predisposing to recurrent genital herpes remain poorly characterized. METHODS In a prospective case-control study, 52 consecutive patients with frequently recurring outbreaks of genital herpes were compared with 80 herpes simplex virus (HSV)-seropositive (types 1 and 2) and 70 HSV-seronegative control subjects. Immunoglobulins (Igs), type-specific anti-HSV-2 IgG and IgG subclass antibodies against glycoprotein G, levels of C3 and C4, and classical pathway hemolytic complement activity were measured, and IgG1 and IgG3 allotyping; C4 immunophenotyping; C4* real-time polymerase chain reaction (PCR) genotyping; and HLA-A*, B*, and DR* typing were performed. RESULTS The G3m(g),G1m(a/a(x)) haplotype was more frequent in patients than in HSV-seronegative control subjects (P=.047). Compared with all control subjects, low levels of total IgG1 (odds ratio [OR], 4.9 [95% confidence interval {CI}, 2.0-12.5]; P=.001) and IgG3 (OR 3.6 [95% CI 1.7-7.8]; P=.001), but not of anti-HSV-2 antibodies, were associated with recurrences. Levels of complement were lowest in patients. The C4* null type was negatively associated with neuralgia (OR, 0.2 [95% CI, 0.06-0.81]; P=.022). CONCLUSIONS Low levels of antibody-dependent cellular cytotoxicity-mediating IgG1 and IgG3 antibodies, partly dependent of allotype, may predispose to recurrent genital herpes. Antibodies produced by T helper type 1 responses, potentially against an unknown epitope, appear to be relevant in recurrences. In patients, C4* deficiencies are associated with protection from herpetic neuralgias, possibly through reduced inflammation.

Allotype-associated differences in concentrations of human IgG subclasses

The concentrations of seven immunoglobulin isotypes (IgA, IgE, IgM, IgG1, IgG2, IgG3, and IgG4) were measured in the sera of 207 Finnish blood donors, and they were allotyped with anti-Gm antibodies: anti-f, anti-a, anti-x, and anti-n. The above population could be divided into 12 phenotypes, and significant differences in isotype concentrations between different phenotypes were observed. They are best explained by postulating that the following alleles of different loci are associated with a high concentration of the product of the locus: a(x)-IgG1, n-IgG2, b-IgG3, and perhaps 4b-IgG4. The following concentration differences between the low and the high homozygotes were found: IgG1, 1.2-fold; IgG2, 1.5-fold; and IgG3, 2.6-fold. No significant allotype-associated differences in the concentrations of IgA, IgM, or IgE could be detected.

Cerebrospinal fluid chemokine CXCL13 in the diagnosis of neuroborreliosis in children

Abstract Background: The diagnosis of Lyme neuroborreliosis (LNB) requires laboratory confirmation because neurological symptoms indicative of LNB are not specific. Recent studies have suggested that a chemokine, CXCL13, could have an important role in the diagnosis of LNB. The aim of this study was to assess CXCL13 levels in the cerebrospinal fluid (CSF) of children with LNB. Methods: CSF samples were available for 57 children with symptoms indicative of LNB. Based on the presence of anti-flagella antibodies and pleocytosis in CSF, patients were divided into 3 different groups: confirmed LNB (n = 24), possible LNB (n = 16), and non-LNB (n = 17). CXCL13 levels were determined with a commercial kit (Quantikine). Results: All 24 patients with confirmed LNB had elevated CXCL13 levels in CSF. Elevated CXCL13 was also observed in the majority of patients without anti-flagella antibodies in the CSF (possible LNB). Of the 17 non-LNB and 50 control samples, 1 was positive. Conclusions: In LNB, the production of CXCL13 in CSF seems to precede antibody production. Assessment of CSF CXCL13 may improve the diagnostics for children with possible LNB.

Mouse IgG antibodies have subclass associated affinity differences.

Subclasses of IgG were separated from pools of mouse sera by letting immunoglobulins absorb on protein A-Sepharose and by eluting with buffers of decreasing pH. Most donor mice were immunized with a conjugate of a hapten (NIP) and chicken gamma globulin 20 days previously. The results indicate that concentrations of IgG varied from 5.1 to 8.6 mg/ml in the pools of immune sera and was 3.0 mg/ml in one normal serum tested. One half of this was IgG1, ca. 20% of IgG2a and IgG2b each, and 10% IgG3 in the pools of BALB/c sera. IgG2a and IgG3 could not be separated from C57BL sera (due to allotype b), but their combined share of IgG appears to be higher than in BALB/c. Immune sera contained 0.5-1.6 mg/ml of anti-NIP antibodies. Of this 90-98% was IgG1 and the remainder was split between the other subclasses. Up to one half of the protein in the IgG1 fraction was anti-NIP antibody. This surprising finding was confirmed by demonstrating that nearly 50% of the u.v.-light absorption was specifically removed by a NIP-immunosorbent. Subclass-associated affinity-differences were observed. IgG1 anti-NIP had a greater average affinity than IgG2a anti-NIP antibodies. The difference was ca. 1.5-fold when the equilibrium dialysis was focusing on the high-affinity bracket of the total population (concentration of free hapten 16-200 nM). At higher hapten concentrations the trend was the same but the data are fewer. Antibodies in subclasses IgG2b and IgG3 appear to share the lower affinity of IgG2a.

A Gene of the Immunoglobulin H‐Chain Cluster Controls the Murine Antibody Response to Pneumococcal Polysaccharide Type 14

Mice of various strains were immunized with pneumococcal polysaccharide type 14 (pneumo‐14), and their anti‐pneumo‐14 antibodies were measured by the Farr test. Mice of strains BALB/c, ST/b, NZB and CBA (Ig allotypes a, e or J) had 300–1700 ng of antibody nitrogen per millilitre of serum on day 7. The corresponding values for C57BL/Ka, RF or AKR mice (allotypes b, c or d) were 40–300 ng/ml. Two families of congenic strains were tested, one with the C57BL and the other with the BALB/c background genome. Their response was either high or low depending on the VH genes, and other gene loci had little effect on the concentration of anti‐pneumo‐14 antibodies.

Concentrations of Serum Immunoglobulins and Antibodies to Pneumococcal Capsular Polysaccharides in Patients with Recurrent or Chronic Sinusitis

A study was carried out to search for underlying immunoglobulin deficiencies in 25 patients with recurrent or chronic sinusitis. The mean duration of the patient histories of recurrent or chronic sinusitis was 7.2 years. Concentrations of serum immunoglobulins and specific pneumococcal antibodies were measured in the patients and in 25 age- and sex-matched control individuals. The mean serum IgA concentration (1.6 g/L) was lower in the patients than in the control individuals (2.1 g/L, p=.024). On the other hand, the mean serum concentration of IgG antibodies to pneumococcal type 14 polysaccharide was higher in the patients (2.54 μg/mL) than in the control individuals (0.92 μg/mL, p=.008). However, elevated concentrations of IgG antibodies to pneumococcal type 14 polysaccharide were detected mainly in patients with the highest serum IgA concentrations. The results suggest that in a subpopulation of patients with a long-lasting history of sinusitis, a low serum IgA concentration may be associated with a susceptibility to sinusitis.

Gm allotypes influence the production of IgG3 but the effect is age-dependent

Serum concentrations of IgG3 were found to be higher in Gm-f-positive (= b-positive) than in f-negative individuals except in young children. Young children aged 3-4 months had a mean concentration of 0.24 g/l of IgG3 regardless of allotype. The concentration gradually rose with age in f-positive individuals to a geometric mean of 0.56 g/l in adults but it remained essentially unchanged in f-negative people. A corresponding allotype effect was seen in influenza-specific antibody responses. While the total IgG response (mainly IgG1) was equally strong in f-positive and in f-negative patients, f-positive (= b-positive) patients produced more IgG3 antibodies than f-negative patients. The difference between geometric mean values of opposite homozygotes (f/f versus f-negative) was 2.3-fold (p = 0.0113). This finding indicates that the b-positive gamma-3 allele is more productive than the g-positive allele.