A hemolytically inactive gene product of factor B.
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Biomedical subjects
Publications and source records attributed to G Hauptmann.
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HLA-A, B, C and Bf antigens were studied in 153 blood donors who developped a titre of greater than or equal to 25 i.u./ml antitetanus antibodies following tetanus anti-toxin vaccination. Antigen frequency was compared with that of 412-464 normal blood donors living in the same area. Few significant differences were demonstrated: absence of Bw21 antigen and slight increase of Bf F antigen were observed in "good responders".
We studied 201 unrelated French Basque individuals for HLA and Bf polymorphisms. The haplotypes of eighty-seven of them were deduced from family studies. The results show the frequency of the Bf F1 allele (0.1393) which is the highest one currently reported. They confirm the high frequencies of HLA-Aw19.2 and B18 previously reported in that population and show that a whole haplotype with strong linkage disequilibria, namely Aw19.2, Cw5, B18, Bf F1, DRw3 is frequent. On the other hand, the gene frequency of Bf S is decreased (0.5497) as compared with the other European Caucasoïd populations, while a slight increase in the Bf F gene frequency (0.2960) appears. These results point out that it is of importance to consider the genetic background choosing the population where linkage disequilibria are to be studied.
The phenotypes Bf were studied in 50 patients (42 men and 8 women) with definite ankylosing spondylitis and in certain of their relatives. The alleles BfF and BfS were most frequently encountered and the rare allele BfF1 in one case only. There may exist a preferential transmission of the haplotype HLA B27- Bf S. In 11 patients without B27 antigen, the distribution of the phenotypes was similar to that in a control group. It is probable that the locus Bf cannot be used as a preferential marker for ankylosing spondylitis.
A detailed gene marker study was performed on a partial 6p trisomic child resulting from a balanced maternal translocation t (2;6) (p 2505; p2105). HLA typing and mixed lymphocyte reaction showed that the breakpoint on chromosome 6 was located within the HLA gene cluster, allowing an accurate location of the D determinants. Localization of the P blood group locus within the region 6 p 2105 to 6 p ter was excluded.
Forty-six members of a family known to have Porphyria were studied. As the disease is often latent clinically, erythrocyte uroporphyrinogen I synthetase activity was determined to classify the subjects as being healthy or carriers. HLA--A, B, C, Bf, GLO antigens were determined. No linkage between acute intermittent Porphyria and the HLA system was noted in this family.
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A patient with an extensive lymphosarcoma of the spleen without involvement of other lymphoid organs and hypogammaglobulinaemia showed the characteristic complement profile of an acquired C1-inhibitor deficiency. Both functional and immunochemical studies revealed extremely low levels of the inhibitor of C1-esterase. Correction of the low levels of early acting complement components and of the low C1-inhibitor level followed the splenectomy. In vitro tests showed that lymphosarcoma tissue pieces or cells were able to interact with complement, resulting in a depletion of the haemolytic activity. These findings provide evidence that tumour cells were responsible for the abnormalities of the complement system.
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Since the discovery of the linkage between HLA and Bf by Allen in 1974 several reports have shown a very close linkage between Bf and HLA-B. We have studied 19 families with 81 offsprings for the linkage between HLA (A,B) and Bf. The total "lod scores" in our material for the linkage between HLA-B and Bf is 17,167 at theta = 0.00. No recombination was observed between HLA-B and Bf. One recombination out of 79 informative meiotic divisions was observed between HLA-A and Bf. This result would mean that the Bf locus is about 1.3% recombination fraction far from the HLA-A locus. Our estimation is in good agreement with the results of other authors. However the estimation of recombination fractions is only an arbitrary mean to map genetic loci on chromosomal regions and family studies of cases with intra-HLA cross-overs are of more interest. All available data from the litterature are in favour to a very close linkage between Bf and HLA-B and to a situation of the Bf locus between HLA-B and HLA-D. However some conflicting data on Bf gene mapping have been published. More precise informations may be obtained as soon as a more exact structure of the HLA region, in particular of the HLA-D region, will be known.
Sera from fourty-six non-congenic adult pigs from one inter-related herd were tested for their haemolytic serum complement levels. A comparison of these data with the major histocompatibility complex (SLA) genotypes of these animals resulted in the demonstration of highly significant differences in lytic activity between sera obtained from animals of two distinct SLA haplotypes. These data showed a high correlation between the SLA complex and the level of haemolytic activity.
An unexpected MLR reaction has been observed between three HLA-identical sibs; it consists of bidirectional positive MLR between identical female twins and a sister. No argument for a lymphoid mosaic could be found, although twins were frequent in the family; similarly no HLA-A/B or HLA-B/D recombinant could be demonstrated. The MLR, although weak, was highly reproducible. PLTs could be raised between the sibs, without an apparent segregation in this family nor in five other families, but such PLTs discriminated well between the positive and negative controls. In the absence of any proof that such a weak MLR locus could be on another chromosome than chromosome 6, two lines of argument are indirect evidences that such a locus could be indeed on chromosome 6: one of the sibs differs from the two others for two markers outside HLA--D--DR--Bf: glyoxalate (GLO) and red blood group P.
In a case of preleukemic dyserythropoiesis, in vitro red cell lysis tests showed a positive acidified serum test whose characteristics are described. The positive acidified serum test occurred in 10 normal sera, in 1 serum with complete deficiency of the fourth component of complement and in 1 serum with complete deficiency of the second component of complement. The test was found negative with 2 hyperlipemic sera. The other in vitro red-cell lysis tests were negative. The results of the in vitro lysis tests were different from the results obtained in paroxysmal nocturnal hemoglobinuria and congenital dyserythropoietic anemias.
In a comparative study the presently known eleven allotypes of properdin factor B (Bf) were examined. Bf polymorphism consists of the two common alleles F and S, the two less common alleles F 1 and S 1 and seven further rare alleles. A variant designation has been proposed according to their relative electrophoretic mobility in comparison to the migration difference between the S and F 1 band. There rare variant alleles were redesignated: F 1.55, SO.45 and SO.7, which previously had been described as F 1.6, S 0.8 and S 1, respectively. Conversion studies did neither reveal variant mobility in the Bb nor in the Ba fragment of factor B in three of the rare alleles. This finding confirms the earlier report on one of the variants, possibly suggesting the existence of a so far unknown third clearing fragment.
A "new" variant band in the Bf system has been found in the serum of three individuals belonging to a tribe of Brazilian Indians (Karaja--Bananal--Goias) and in the serum of a Caucasian individual from the area of Strasbourg. It is highly probable that the band represents another allele at the Bf locus BfS0.8.
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Homozygous typing cells (HTC) for two new HLA-D determinants, EI and RE, defined by family studies, are described. The HLA-D typing experiments among more than 300 unrelated individuals showed phenotype frequencies of 0.045 for EI and 0.098 for RE. Since the tested population was also typed for its HLA-A and -B alleles, linkage disequilibrium parameters could be calculated: HLA-D type EI was statistically significantly associated with HLA-B13 and Bw17, HLA-D type RE with HLA-Bw40. These data support the working hypothesis that both EI and RE are new alleles of the HLA-D series.