Perspectives and future directions. Immunogenetics

An outline of the history of immunogenetics is presented. The usefulness of the Rh, HLA and Gm systems in disease prediction and prevention will increase with our capacity precisely to relate polymorphic variants to particular functions and pathophysiological events. Alloimmunization to Gm markers is common in rheumatoid arthritis, an allegedly autoimmune disease. This paradox and the paradox of nonnominal allotypes, disobeying Mendelian rules, are resolved by the interpretation that herpesviruses may transfer nonself polymorphic genes. Transduction of such genes may be important also in AIDS pathogenesis.

Advances in human immunoglobulin allotypes

Monoclonal anti-Rh's and monoclonal anti-Gm's are now available, permitting a more precise serological determination of the human allotypes. Several Gm allotypes can be determined at the gene level, without resort to serological reagents. PCR, subclass-specific amplification and allele-specific probes are used. Many RFLPs of the human IgH C- and V-region genes have now been defined. More than 10(6) variant haplotypes of the so-called constant part of the Ig chain are possible because more than 20 polymorphic sites are known. A schematic physical map of the human IgHC gene cluster is presented.

Abstract LB-337: Synergistic effects of twelve common genetic polymorphisms and smoking habits on absolute risk of bladder cancer

Smoking is the strongest established risk factor for bladder cancer and recent studies have identified multiple common susceptibility loci for this disease. Evaluation of gene-smoking interactions on absolute risk of bladder cancer could be important for understanding both the public health and biological significance of the combined effect of these factors. However, previous studies of gene-environment interactions focused on relative rather than absolute risk measures and thus did not address this important question. The aim of our analyses was to estimate absolute risk of bladder cancer in relation to smoking habits and 12 known susceptibility variants for this disease, and to evaluate if smoking risk differences (RD) vary by levels of a polygenic risk score derived from these variants, using additive tests for interaction. Analyses were based on data from 4,098 cases and 5,995 controls of European background in eight studies participating in the NCI bladder cancer genome-wide association study (GWAS). Absolute risks were estimated based on US incidence and mortality data. The main outcome measures were 30-year cumulative absolute risk of bladder cancer and RDs for males aged 50 years in relation to smoking habits and the polygenic risk score. RDs for ever compared to never smokers were significantly larger (P-additive interaction < 0.05) for subjects carrying risk alleles for seven out of 12 known susceptibility variants. Polymorphisms in two detoxification enzymes, NAT2 and UGT1A6, provided the strongest evidence of additive interactions (P-additive interaction of 0.0002 and 0.0003, respectively), supporting the presence of biological interactions between smoking and these variants. The 30-year risk of bladder cancer in never, former and current smokers was 0.7%, 1.6% and 3.7%, respectively, for subjects in the bottom quartile of the polygenic risk score, compared to 2.0%, 5.1% and 8.0% for subjects in the top quartile. This translates into a significantly larger number of projected cases, which could be avoided by smoking prevention in subjects at higher compared to lower genetic risk (P-additive (2df)=4.6x10-9 for top to bottom quartile of the polygenic risk score). In conclusion, our analyses provide strong evidence for synergistic effects of smoking and known susceptibility loci for bladder cancer on the absolute risk of the disease. This indicates that targeting intense smoking prevention efforts to individuals at elevated genetic risk for bladder cancer could improve the public health impact of such efforts. However, genetic susceptibility for other smoking-related diseases, as well as practical and ethical considerations, would need to be taken into account before any recommendations could be made. (MGC, NR are Co-first authors; N.C. and DTS are Co-last authors)

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-337. doi:1538-7445.AM2012-LB-337

Novel mutations in FH and expansion of the spectrum of phenotypes expressed in families with hereditary leiomyomatosis and renal cell cancer

BACKGROUND

Hereditary leiomyomatosis and renal cell cancer (HLRCC; OMIM 605839) is the predisposition to develop smooth muscle tumours of the skin and uterus and/or renal cancer and is associated with mutations in the fumarate hydratase gene (FH). Here we characterise the clinical and genetic features of 21 new families and present the first report of two African-American families with HLRCC.

METHODS

Using direct sequencing analysis we identified FH germline mutations in 100% (21/21) of new families with HLRCC.

RESULTS

We identified 14 germline FH mutations (10 missense, one insertion, two nonsense, and one splice site) located along the entire length of the coding region. Nine of these were novel, with six missense (L89S, R117G, R190C, A342D, S376P, Q396P), one nonsense (S102X), one insertion (111insA), and one splice site (138+1G>C) mutation. Four unrelated families had the R58X mutation and five unrelated families the R190H mutation. Of families with HLRCC, 62% (13/21) had renal cancer and 76% (16/21) cutaneous leiomyomas. Of women FH mutation carriers from 16 families, 100% (22/22) had uterine fibroids. Our study shows that expression of cutaneous manifestations in HLRCC ranges from absent to mild to severe cutaneous leiomyomas. FH mutations were associated with a spectrum of renal tumours. No genotype-phenotype correlations were identified.

CONCLUSIONS

In combination with our previous report, we identify 31 different germline FH mutations in 56 families with HLRCC (20 missense, eight frameshifts, two nonsense, and one splice site). Our FH mutation detection rate is 93% (52/56) in families suspected of HLRCC.

Paramedics can apply and read Mantoux tuberculosis tests

Selected paramedics (26) received 2 h of training in the application and interpretation of Mantoux skin tests by a specially trained registered nurse. Instruction included a lecture, a video tape, and practice skin test administration on "induration arms." All students successfully completed written and skills tests. During a follow-up period, registered nurses directly observed skin test application and interpretation by the paramedics when applying the skin test to other departmental fire fighters and compared these to set criteria. Interpretation of skin test results included appropriate referral for positive results. Paramedics administered 319 skin tests during subsequent follow-up and 305/319 (96%) were monitored by a registered nurse. All administration criteria were performed as indicated 100% of the time except for the criterion requiring a 5-10 mm wheal. The application was appropriately repeated in each case. In one application, a paramedic began to use the same needle and syringe to draw up additional solution, but was immediately corrected. Among 227 cases of test interpretation by paramedics, paramedics were monitored by a registered nurse in 169 interpretations (74%). All monitoring criteria were performed as indicated 100% of the time. Nurses concurred with each monitored measurement. Induration results were 0 mm, 216 tests; 1-9 mm, 9 tests; > or =10 mm, 2 tests. Appropriate follow-up was provided to the two individuals with > or =10 mm induration. The results indicate that paramedics can successfully apply and accurately interpret Mantoux skin tests on public safety employees, although the number of positive tests was low, reducing the reliability of the findings.

Calibration of an extreme-ultraviolet transmission grating spectrometer with synchrotron radiation

The responsivity of an extreme-ultraviolet transmission grating spectrometer with silicon photodiode detectors was measured with synchrotron radiation. The spectrometer was designed to record the absolute radiation flux in a wavelength bandpass centered at 30 nm. The transmission grating had a period of 200 nm and relatively high efficiencies in the +1 and the -1 diffraction orders that were dispersed on either side of the zero-order beam. Three photodiodes were positioned to measure the signals in the zero order and in the +1 and -1 orders. The photodiodes had aluminum overcoatings that passed the desired wavelength bandpass centered at 30 nm and attenuated higher-order radiation and wavelengths longer than approximately 80 nm. The spectrometer's responsivity, the ratio of the photodiode current to the incident radiation power, was determined as a function of the incident wavelength and the angle of the spectrometer with respect to the incident radiation beam. The spectrometer's responsivity was consistent with the product of the photodiode responsivity and the grating efficiency, both of which were separately measured while removed from the spectrometer.

Rheumatoid arthritis--a gene transfer disease

Sera from patients with rheumatoid arthritis (RA) were from the very start instrumental in detecting and delineating the human immunoglobulin (Ig) allotypes in the Gm system. Knowledge that human Ig production is under Mendelian control and not determined by templates of antigen would not have come to the fore if it were not for RA patients. Worldwide experience shows that RA patients are prone to mount an immune response to human Ig allotypes. Major Gm allotypes are defined at the amino acid and nucleotide levels. Gene technology has been developed for defining these allotypes. Studies of the Gm allotypes and anti-Gms have led to two apparently paradoxical findings: (1) In conflict with Mendelian law, non-nominal or hidden allotypes have been observed and recently documented at the DNA level. (2) In RA, an immune response to other individuals' Mendelian allotypes is prevalent, although RA is generally considered an autoimmune disease. These findings led us to conclude that RA is not initially an autoimmune disease but a gene transfer disease. A brief review of viral high-jacking and transfer of human genes is given along with reasons for considering the herpesvirus family in particular. Genes determining incompatible Ig allotypes are transferred. We have shown that these genes are expressed in RA synovia. Ig-anti-Ig complexes arise and may have arthritogenic potential, as observed in serum sickness.

Nucleotide sequences specific for nonnominal immunoglobulin allotypes in rheumatoid arthritis patients and in normal individuals and their expression in synovial tissue of rheumatoid arthritis patients

The production of antibodies against nonnominal immunoglobulin allotypes in rheumatoid arthritis (RA) patients suggests that the immune system of these patients has been exposed to such foreign allotypes. The presence of nonnominal allotypes is, however, a genetic enigma. We searched for nucleotide sequences specific for nonnominal G3mg and G3mb copies in individuals homozygous for these alleles. Using a sensitive and specific nested polymerase chain reaction (PCR) method with genomic DNA from blood of 18 RA patients and 5 normal controls, we found G3mg sequences in 18 of 18 tested G3mb homozygous persons. The allele specificity of the PCR fragments was confirmed by sequencing and RFLP analysis. The PCR products contained genomic nonspliced parts of the nonnominal sequences. An analysis of cDNA from inflammatory tissue of 5 RA patients detected nonnominal G3mb sequences in 1 of 3 tested G3mg homozygotes and G3mg sequences in 2 of 2 tested G3mb homozygotes. The cDNA-derived PCR products contained sequences from normally spliced nonnominal Ig fragments. The results also showed that the nonnominal Ig sequences were present in very low copy numbers, lower than the Mendelian 1-2 copies per cell. The origin of such a low copy number of Ig gene fragments may be explained by a virus-mediated capture and transfer mechanism of Ig gene fragments generated by the normal Ig switch-associated gene excision process.

DNA sequences specific for Caucasian G3m(b) and (g) allotypes: allotyping at the genomic level

Assignment of the G3m(g) and (b) correlative amino acid residues was performed at the genomic level by direct sequencing of DNA from nine Caucasian individuals. Two oligonucleotide primers were used for subclass-specific enzymatic amplification of a DNA segment comprising a major portion of the second and third constant region domains (CH2 and CH3) of the human IgG3 heavy chain gene. Comparison of the sequences of amplified DNA from individuals serologically typed as homozygous for G3m(b) or G3m(g) or as heterozygous, G3m(b,g), revealed differences in the codons for the amino acid residues 291, 296, and 384. Proline, phenylalanine, and serine at these positions corresponded to G3m(b), and leucine, tyrosine, and asparagine to G3m(g). Heterozygotic individuals, typed G3m(b,g), displayed both the G3m(b) and G3m(g) codons at these three positions. The polymorphism at each of these three codons could be identified either as the appearance, or the loss, of recognition sites for the two restriction endonucleases, Nsp BII and Rsa I. This allowed the development of a polymerase chain reaction (PCR)-based assay permitting the distinction of G3mb and G3mg alleles by analyzing the electrophoretical mobility of the DNA fragments generated by digestion of the PCR-products with Nsp BII and Rsa I.

HLA-DR antigens, Gm allotypes and antiallotypes in early rheumatoid arthritis--their relation to disease progression

OBJECTIVE

Evaluation of the prognostic value of immunogenetic markers in early rheumatoid arthritis (RA).

METHODS

Ninety-nine patients with definite RA and disease duration 24 months or less were followed with standardized assessment. Disability was assessed by the HAQ index and radiographic changes in hands and feet by the Larsen method. The frequencies of HLA-DR genes were determined by serological typing, Gm allotype distribution by classical hemagglutination inhibition test, and occurrence of anti-Gm allotypes by use of anti-Rh coats. The immunogenetic findings were related to disease severity after 2 years' followup.

RESULTS

Functional capacity was well preserved, disease activity was less, but radiographic changes in hands and feet had increased considerably at study finish. A group of 13 patients had developed rapidly progressive changes of hip and/or shoulder joints, all requiring arthroplasty. There was a significantly increased frequency of HLA-DR4. Twenty-seven of the 68 HLA-DR4 positive patients were putatively homozygous. HLA-DR4 was not related to disability or to severe small joint destruction. However, progressive large joint damage was significantly more prevalent in homozygous patients (p < 0.01). Gm allotype distribution was normal and not related to clinical findings. Anti-Gm antibodies were common and frequently specific for nonhost Gm allotype. Fifty-six patients carried anti-G1m(a), and occurrence of this antibody was significantly associated with radiographic progression of small joints (p = 0.01), presence of nodules (p < 0.01) and number of active joints (p = 0.001).

CONCLUSION

Immunogenetic markers aided in identifying patients with early RA with more severe disease.

Herpesvirus serology, aberrant specific immunoglobulin G2 and G3 subclass patterns and Gm allotypes in individuals with low levels of IgG3

One objective of this study was to determine whether IgG3-deficient individuals have an increased frequency of reactivated herpesvirus infections. Serum titres to Epstein-Barr virus (EBV) and human herpesvirus-6 were examined in 10 healthy and in 10 symptomatic persons with serum IgG3 < 0.1 g/l. Atypical titres were found in 16% of the IgG3-deficient individuals. Reactivations of these viruses thus do not seem common in IgG3 deficiency. Antigen-specific IgG responses were also determined. A lowered frequency of IgG3 to an EBV-derived peptide was found only in symptomatic, IgG3-deficient individuals. Levels of IgG2 to a bacterial polysaccharide were lowered in the same group, despite normal serum levels of total IgG2. A functional IgG2 deficiency may contribute to symptoms in IgG3 deficiency. The G3(g) allotype, known to be associated with low total IgG3, dominated in IgG3-deficient persons (13/17) independently of presence or absence of symptoms. A linkage of G3(g) to the G2(n) negative allotype, associated with low IgG2, was equally common irrespective of symptoms. G3(g) and absence of G2(n) seem to be one prerequisite for most of IgG3 deficiency combined with low specific IgG2.

The clinical application of neurogenic motor evoked potentials to monitor spinal cord function during surgery

The purpose of this study was to report results from 300 cases (177 children, 123 adults) administered somatosensory and neurogenic motor evoked potentials during surgery. Of these 300 cases, there were 16 cases of spinal fractures, 16 neurosurgical cases, 28 vascular cases, and 240 cases of elective posterior spinal deformity requiring instrumentation. Results indicated that somatosensory evoked potentials, especially cortical components, demonstrated greater variability than neurogenic motor evoked potentials. Variability was attributed to anesthesia and unknown factors. Neurogenic motor evoked potentials proved to be a more valid indicator of postoperative motor status than somatosensory evoked potentials. Based on their anatomic substrates and results from this study, it was recommended that somatosensory evoked potentials and neurogenic motor evoked potentials be used to monitor spinal cord function during surgery that would place that structure at risk.

Immunogenetic markers as probes for polymorphism, gene regulation and gene transfer in man--the Gm system in perspective

The genetic markers of immunoglobulins (Ig) demonstrable by immunological methods have shown their usefulness as genetic probes. The study of these allotypes originally proved that Ig production is under conventional genetic control and also established that allelic exclusion is valid for the key molecules of the immune response. The codons responsible for the G1m(a) marker and their position in the human genome are precisely known. This knowledge implies that Gm typing may be used as a convenient and reliable means of following the fate of IgG constant gene segments. Anti-Gm's are common in rheumatoid arthritis. They appear early in the disease and may persist throughout life. The stimulus for their appearance has not yet been established. The anti-Gm's in the allegedly autoimmune disease rheumatoid arthritis are commonly and apparently paradoxically specific for Gm gene products of other persons. Another apparent paradox brought to light by Ig allotype research is the occasional appearance of non-nominal allotypes in contradiction to Mendelian laws. It is proposed that a plausible explanation for these two paradoxes is Ig gene transfer between individuals with viral vectors. Reasons for this proposal and some possible consequences of gene transfer in a polymorphic species are delineated. Immunogenetics and DNA technology in combination provide powerful tools to elucidate the fate of genes. A method allowing the assignment of G1m(a+) and G1m(a-) at the gene level by polymerase chain reaction analysis has recently been established and is briefly described.

Distribution of Gm allotypes in juvenile chronic arthritis

The immunoglobulin allotypes G1m(a), G1m(x), G2m(n), G3m(b) and Km(1) were determined in 76 Swedish patients with juvenile chronic arthritis (JCA). Eight of the patients had the systemic form of the disease. 37 belonged to the polyarticular and 31 to the oligoarticular subset. The frequency of the G1ma(x), G3m-b haplotype was significantly increased in the polyarticular subset but not in the oligoarticular subset, compared with the normal population (p less than 0.01). The polyarticular subset also differed from the oligoarticular subset with increased frequency (p less than 0.01) and higher levels (p less than 0.01) of IgM rheumatoid factor and a lower rate of remission (p less than 0.05). The few JCA patients in the systemic subset showed similar features as the polyarticular patients. The frequencies of G2m(n) and Km(1) did not deviate from the expected in any of the JCA subsets.

The Gm system. Anti-Gm's: characteristics in rheumatoid arthritis; experimental induction without resort to allotype; frequent occurrence in mononucleosis

Gm system: Some RFs specifically detect Mendelian markers of human Ig, originally proving that Ig production is gene controlled. The genetic marker systems of human Ig with 17 Gm, 2 Am, 3 Km and 1 Em markers are briefly described. Examples of the usefulness of the Gm system in medicine, immunology and molecular biology are mentioned.

CONCLUSIONS

1. Some RFs have been essential tools in elucidating genetic control mechanisms in Ig production. 2. Knowledge of the Gm system is extensive. Anti-Gm's: High-titered anti-Gm's are common in R.A. The anti-allotypes in R.A. are markedly restricted as to their specificity. They are usually not directed against the individuals own Gm markers. Anti-human-immunoglobulins were observed in 12 of 18 sera from patients with mononucleosis. The majority of these anti-immunoglobulins were inhibitable by native human Ig and showed restricted specificity.

CONCLUSIONS

1. There is a strong stimulus for production of particular anti-Gm's in a majority of R.A. cases. 2. Notions of an autoimmune origin for many anti-Gm's in R.A. are not in obvious agreement with experimental observations. 3. Anti-human-Ig's with restricted specificity are commonly induced in mononucleosis.

Incidence of anti-human Ig with restricted specificity in Japanese, Kuwaiti, and Swedish patients with rheumatoid arthritis

Assuming that anti-allotypic anti-Ig in rheumatoid arthritis is stimulated by the individual's allotype, it would be reasonable to expect a higher incidence of anti-G1m(a) in individuals carrying G1m(a). There is marked divergence among various populations in allotype frequencies. G1m(a) allotype and the prevalence of anti-Ig reactive with G1m(a) Ig were determined in 18 Kuwaiti, 23 Japanese, and 41 Swedish rheumatoid arthritis patients. An inverse relationship was observed between the frequency distribution of allotype G1m(a) and anti-allotype; thus, the stimulus for the anti-allotype is not the patient's own allotype.

Failure of doxycycline treatment in aquarium-associated Mycobacterium marinum infections

Two cases of aquarium-associated Mycobacterium marinum infections are described. Neither was cured by the initial therapy consisting of surgical excision followed by doxycycline treatment. Both strains of M. marinum were shown to be resistant to doxycycline. In one patient the lesions were subsequently healed with cotrimoxazole. The other patient, a 12-year-old girl with sporotrichoid spread of the lesions on the lower arm, failed to respond satisfactorily to a combination of rifampicin and ethambutol despite favourable effect in vitro of both drugs. Nine months after the initial treatment, the infection was finally cured with renewed surgery followed by additional chemotherapy with rifampicin and ethambutol. No signs of immunological disorder could be detected in the patient. Increased awareness of the possibility of tetracycline resistance of M. marinum is advocated. A combination of adequate chemotherapy and surgical intervention may be required at least in complicated cases.

Correlation between deficiency of immunoglobulin subclass G3 and Gm allotype

Gm allotypes were investigated in 63 Swedes: 46 females and 17 males, in whom serum IgG3 was below 0.35 g/l. Both monoclonal antibodies and polyclonal antisera were used for the quantification. Concentrations of the other IgG subclasses were within the age-related normal ranges. The distribution of the IgG1 genetic markers G1m(a,x,f) differed markedly from that observed in normal Swedes (p less than 0.001). Thus G1m(a) was present in 60 subjects as compared to an expected 36, and phenotype G1m(-f) in 34 subjects as against an expected 8. The mean IgG3 concentration was numerically lower in the G1m(-f) group than in the G1m(+f) cohort, and individuals with IgG3 levels 0.10 g/l were more frequent in the G1m(-f) group. Among Caucasians, G3mg is in linkage disequilibrium with G1ma and our interpretations is that the haplotype G1ma;ax G2m-n G3mg is markedly increased in individuals with IgG3 deficiency.

Familial occurrence of cervical cancer, stages 0-IV

All patients hospitalized in 1982 at the Department of Gynecology in Malmö because of malignancy of the cervix uteri attended an interview study concerning the presence of cervical cancer among their nearest relatives. In addition, these patients were questioned concerning earlier gonorrheal infection. The blood group was determined as also was the secretory status and Gm allotype. As a control group the families of the male consorts were used. Cervical cancer was found significantly more often in mothers of the patients (7.9%) than in the consorts' mothers (1.0%). Sisters, aged 20 or over, of the patients had cervical cancer significantly more often (7.5%) than sisters of the consorts (1.1%). Moreover, cervical cancer in mothers and/or sisters was found in 15.6% of the patients. In cases of invasive cancer or previously operated CIS, this figure was 17.5%. The patients did not differ significantly from the normal population regarding blood group or secretory status. A somewhat lower, although non-significant, frequency of Gm(1) allotype was found in patients with invasive cancer, compared with patients with CIS. Patients with a positive family history of cancer had more often had gonorrhea (24%) than patients with a negative family history (18%). The study indicates a multifactorial etiology for cervical cancer.

Gm allotypes in IgA deficiency

Gm phenotypes were examined in 90 Swedish IgA-deficient (less than 0.05 g/litre of serum IgA) donors and 40 normal first and second degree relatives of six of these donors. The G1m1,2, G3m5 and Km1 frequency in the group of IgA-deficient donors did not differ from that found in the normal population. Among the relatives, HLA and/or Gm identical normal sibs were observed. Anti-IgA antibodies were present in 29 of the IgA-deficient donors and anti-IgG in seven. No association between the two was found. A statistically significant association between the G1m-2 phenotype and the presence of anti-IgA antibodies was observed. When subdivided according to HLA type, a non-random distribution of Gm phenotypes was seen in HLA-B8/DR3 positive individuals with anti-IgA antibodies (HLA-B8/DR3 being the haplotype associated with IgA deficiency). These data suggest an association between IgA deficiency, anti-IgA and the studied Gm allotypes.

Anti-immunoglobulins in experimental streptococcal immunization; relation to bacterial growth conditions and Fc-receptors

Heat-killed group A streptococci of types M12 and M22 were used for intravenous immunization of 60 rabbits. Presence of Fc-receptors binding monomeric IgG in M22 and their absence in M12 has been demonstrated previously. The strains were cultured in either Todd-Hewitt broth supplemented with 10% horse serum (TH-H) or in IsoVitaleX, a synthetic medium, supplemented with 10% autologous rabbit serum (IV-R). A mortality rate of 38% was noted in the first-mentioned group whereas no mortality was observed in the second group. Sera were examined for agglutination of red blood cells coated with either human or rabbit IgG. Antisera to strains cultured in TH-H regularly displayed anti-IgG antibodies reacting with human as well as rabbit IgG; anti-rabbit IgG titres of anti-M22 sera were significantly higher than those of anti-M12. Antisera to strains grown in IV-R displayed high levels of antibodies reacting with human but not with rabbit IgG. The levels of anti-human IgG did not differ between anti-M12 and anti-M22 sera.

Gm allotypes in Finnish myasthenia gravis patients

Gm phenotype G1m 1,2, and 3 frequencies were examined in 103 Finnish myasthenia gravis patients. There were no significant differences as compared with the expected frequency, either in the total material or when patients were subdivided according to sex, age of onset of disease, thymus pathology, or presence of HLA-B8. However, individuals with Gm(+1) had a significantly higher concentration of antibodies against acetylcholine receptor, possibly indicating a correlation with severity of disease.

Gm allotypes in Swedish myasthenia gravis patients

Gm phenotype frequencies were examined in 112 Swedish myasthenia gravis patients. The G1m 1,2,3 phenotype frequency in the total patient material did not differ significantly from that found in the normal population. However, when patients were subdivided, three different patient groups were observed with regard to Gm1 frequency: (1) Thymoma patients having a low frequency of Gm1, (2) Non-thymoma patients with a mild disease having a low frequency of Gm1 and (3) Non-thymoma patients with a severe disease having a high frequency of Gm1. When patients were subdivided according to presence or absence of HLA-B8 and Gm1 respectively, severe symptoms were less frequent in the HLA-B8+, Gm(-1) group as compared to the HLA-B8+, Gm(+1) group. Furthermore, there was an increased frequency of sera with anti-immunoglobulins not inhibitable by pooled control immunoglobulins.

Association between maternal Gm allotype and neonatal septicaemia with group B streptococci

Thirty-four mothers to infants seriously infected with group B streptococci (GBS) were investigated for G1m (1) and G3m(5) allotype markers. The frequency of Gm (1, -5) was 14.7%, of Gm(1,5) 20.6% and Gm (-1, 5) 64.7%. There was a marked deficit Gm (1) individuals and the distribution significantly differed from that in the normal Swedish populations.

Isolation and some properties of an IgG Fc-binding protein from group A streptococci type 15

An IgG Fc-binding protein was isolated from alkaline extracts of group A streptococci type 15 by ion-exchange chromatography and immunosorption on an IgG column. Ample use of protease inhibitors was necessary to achieve successful isolation. 600 micrograms protein was obtained from 60 g bacteria (wet weight). The protein appeared homogeneous on agarose gel and sodium dodecyl sulfate polyacrylamide gel electrophoresis and had an apparent molecular weight of 29,500. It contained appreciable amounts of the amino acids glutamic acid, alanine, leucine, aspartic acid and lysine, but little or no tyrosine, phenylalanine, proline, glucosamine or galactosamine. It precipitated human monoclonal IgG of all four sub-classes in agarose gels as well as polyclonal IgG, IgG Fc and normal human serum. It did not precipitate IgG Fab, IgA, IgM, IgD or free kappa or lambda chains.

Convenient synthesis of 6-nor-9,10-dihydrolysergic acid methyl ester

6-Nor-9,10-dihydrolysergic acid methyl ester (IV) was prepared by demethylation of 9,10-dihydrolysergic acid methyl ester (II) with 2,2,2-trichloroethyl chloroformate, followed by reduction of the intermediate carbamate (III) with zinc in acetic acid. The 6-ethyl-V and 6-n-propyl-VI derivatives were prepared by alkylation of IV with the appropriate halide. All of the ergoline derivatives were evaluated for stereotyped behavior in rats, with 6-nor-6-ethyl-9,10-dihydrolysergic acid methyl ester (V) being active but much less potent than apomorphine. Compound VI was evaluated for its effect on blood pressure; at a dose of 30 mg/kg ip, it significantly lowered, diastolic pressure in normotensive rats.

IgG-Fc-receptors in T-type 12 group A streptococci from clinical specimens: absence from M-type 12 and presence in M-type 22

Eighty-eight T-type 12 group A streptococcal strains were randomly selected from routine specimens in two epidemiologically unrelated districts. All of 26 M-type 12 strains lacked IgA and IgG Fc-receptors, whereas all 32 M-type 22 strains had IgG Fc-receptors and 20 of them also receptors for IgA Fc. The remaining strains were not further M-typed but 18 of these 30 strains exhibited receptors for IgG and 13 for IgA.

IgG F(ab')2 of rabbit anti-M sera but not the unfractionated sera are bactericidal for some group A streptococci with IgG Fc-receptor activity. Opsonic effect ascribable to anti-IgG

We have earlier reported on a group A streptococcal strain, type M12, which upon serial mouse passage acquired IgG Fc-receptor activity but lost the M-antigen. The passaged strain, 12P, was highly virulent for mice and grew well in normal human blood. The present study particularly concerns the opsonic effect on 12P of rabbit anti-M3, anti-M12 and anti-12P sera, as well as the corresponding IgG F(ab')2. Indirect bactericidal tests showed that the homologous anti-12P seum and IgG F(ab')2 were opsonic. The anti-M3 and anti-M12 had no effect on 12P; surprisingly, however, IgG F(ab')2 isolated from these sera displayed a clearcut opsonic activity. Data are presented which indicate that these "paradoxical" results can be explained by the binding of IgG F(ab')2 with anti-IgG specificity to human IgG, linked to the streptococcal surface through Fc-receptors. Only anti-12P serum, or IgG F(ab')2, were protective for mice on challenge with strain 12P.

Changes in virulence, M protein and IgG Fc receptor activity in a type 12 group A streptococcal strain during mouse passages

A type 12 group A strain (1800) was passaged serially through mice 25 times. The ability to servive in normal human blood dropped from a growth index of 52 after the first passage to 1 after four passages. After 14 passages the growth index increased again and stabilized above 30. The virulence for mice increased from a LD100 of 10(8) colony forming units (CFU) to 10-100 CFU after 7 passages and then remained constant. The Mqw antigen disappeared after 4 passages as tested by immunodiffusion, electroimmunoassay and indirect bactericidal tests. Three antisera, raised in rabbits against strains originally belonging to types M3, M12 and M46 but devoid of type antigens after mouse passages showed high bactericidal indices against the 1800 strain after 14 or more passages on mice. Anti-type M1 serum was also found bactericidal for the passaged strains. The IgG Fc-receptor activity of the strain isolated after each mouse passage was tested in hemagglutination experiments with human red blood cells coated with "incomplete" anti-Rh and hot hydrochloric acid extracts of the strains. The capacity to agglutinate "Ripley"-coated cells increased gradually during the first 12 passages and subsequently the titres of the extracts stabilized between 1:160 and 1:320. The HUN coat, useful for detection of the G3m (5) maraker gave titraes increasing with the number of passages while the titres for IgG1 coats kept at 1:4 or below. On background of these results, the possible role of the IgG Fc-receptor as a virulence factor is discussed.

Interaction of the Fc part of IgG with Lancefield extracts of hemolytic streptococci. Strain specificity and activity

Lancefield extracts of 19 types of group A streptococci as well as one group C and one group G strain were examined for agglutination of human red cells coated with various anti-Rh antibodies. Fourteen extracts agglutinated one or more of the coated cell samples, while five did not. The agglutination was inhibited by Fc but not by Fab fragments of human IgG. After mouse passages, three of the non-agglutinating strains acquired agglutinating capacity. At least three different reactivities were distinguished by the action of the extracts on IgG1 and IgG3 coated cells, respectively. Two of the streptococcal extracts, agglutinating the same anti-Rh coated cells, could be further differentiated in hemagglutination inhibition (HAI) experiments using purified IgG3 myeloma proteins. Five selected agglutinating systems were inhibited by purified myeloma proteins of the IgG1, IgG2, and IgG4 subclasses. IgG3 proteins inhibited only two of the five HAI systems.

Lancefield extract of group A streptococci type 15 acts like an anti-human IgG with restricted specificity

Lancefield extract of streptococci group A type 15 precipitates certain human sera and agglutinates red cells coated with some IgG anti-Rh antibodies. The frequency of precipitation varies between populations. The serum component in the precipitate is IgG. The results indicate that an iso-allotypic marker is detected by the extract.