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The sequence of a novel allele, HLA‐B*57:71, differs from HLA‐B*57:01:01 by three‐nucleotide exchanges in exon 2. [ABSTRACT FROM AUTHOR]

HLA-DP genotyping with sequence-specific oligonucleotides can detected known sequence variations in the polymorphic segments of the DPB1 second exon. Since the allelic polymorphism of the 22 published alleles is based on recombination of sequence motifs from six variable regions, DPB1 typing depends on the reactivity pattern of many different probes rather than from typing with single allele-specific probes. By computer simulation, we have previously shown that the minimal set of probes to define the 22 different alleles and most of the heterozygous combinations is 18. Here we describe HLA-DPB1 typing results and allele frequencies in a panel of 200 unrelated Caucasians from Southwest Germany. The result confirmed the power of the new HLA-DPB1 typing method, but we failed to detect three of the previously described alleles in our panel. To accommodate with the observed 19 different alleles, the sequence and hybridization conditions of 17 oligonucleotide probes are given, which are able to differentiate all except two, resolved by group-specific amplification, of the 190 possible heterozygous phenotypes.

A selective screening program has been established to identify rapidly and effectively the fine specificity of HLA-DR antibodies in pregnancy anti-HLA sera. Following initial HLA-A, B, C screening sera with extra- or multispecific reactions were selected and specifically tested after platelet absorption on isolated B- and T-lymphocyte populations of the serum donor's husband. Identification of the HLA-DR serum. Multispecific anti-DR sera were defined and rendered operationally monospecific by titration. Some critical steps in a reliable assessment of HLA-DR typing reagents could be worked out. Weak HLA-A, B antibodies, B-cell auto- and Lewis antibodies may cause positive reactivity preferentially or even selectively on B lymphocytes. Of particular importance was the hidden presence of HLA-C specific antibodies, since they cannot be absorbed out of stored platelets. In addition they are not readily detectable through screening on typed panel cells. Because of the frequently very high linkage disequilibrium between HLA-B and HLA-C alleles it is difficult to select appropriately dissecting panel cells. The two points demonstrated above gain even more weight when isolated T and B cell populations are used for HLA-DR typing, because HLA-C antibodies preferentially kill B cells. In this fashion contaminating HLA-C antibodies are not only difficult to detect but can mimic the presence of HLA-DR antibodies.

The present study investigated the distribution of HLA-antigens and Bf alleles in a group of 21 patients suffering from biopsy proven Idiopathic Membranous Nephropathy (IMN). A statistically significant increase of HLA-DR3 (76.2%) was detected in the patient group as well as an increase of MT-2 (86%), which is a new supertypic specificity defined within the 8th International Histocompatibility Workshop 1980. No association between BfF1 and IMN can be deduced from this study. Only the common Bf alleles (BfFF, BfFS, BfSS) were found in the patient group presented here. Also the previously reported association between HLA-B18 and IMN was not corroborated by this study. Not a single IMN-patient typed positive for HLA-B18. Thus the presence of two different HLA-DR-Bf-B linkage groups (HLA-DR3/BfF1/HLA-B18 and HLA-DR3/Bf; all alleles/HLA-B8) may point to at least two different immunological mechanisms underlying IMN.

Cells from the human immature monocytoid cell line U-937 were induced with 12-O-Tetradecanoyl-phorbol-13-acetate (TPA) to differentiate towards macrophage-like cells. The expression of HLA-antigens during differentiation was examined with a panel of monoclonal antibodies directed against monomorphic and polymorphic determinants. Class II antigens could be detected neither on uninduced nor on TPA-induced U-937 cells. While the expression of HLA-A3 did not change significantly during differentiation, the "supertypic" specificities HLA-Bw4 and Bw6 as well as the "private" specificity HLA-B18 could be detected only on a drastically decreased number of cells after 4 days of exposure to TPA. This may imply a selective loss of HLA-B molecules from the cell membrane and therefore a separate regulatory control of HLA-A and -B antigens.