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.