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The leukocyte immunoglobulinlike receptor ( LILRA3 ; ILT6 ) gene is localized on human chromosome 19 in the region 19q13.4, in the leukocyte receptor complex that encodes leukocyte receptors LILR (ILT/LIR), killer cell immunoglobulinlike receptors (KIR), LAIR, Fc IgA receptor, and others. The biologic role of the LILRA3 molecule and the nature of its ligand are not known. Comparison of LILRA3 gene sequence with those of other LILRs suggests LILRA3 is a soluble molecule. If LILRA3 binds human leukocyte antigen (HLA) class I molecules like other LILRs whose ligands are known, then it might block recognition of HLA by these receptors, influencing immune response and susceptibility to HLA class I associated disease. A deletion of LILRA3 gene was found in a minority of British population. We typed 108 healthy individuals from the Low Silesia region and 103 patients diagnosed with psoriasis vulgaris (a disease associated with HLA class I antigen, HLA-Cw6) for LILRA3 to examine whether LILRA3 deletion was distributed differently in patients affected with the disease. No differences in frequencies of the LILRA3 deletion were found between controls and patients or between HLA-Cw6 + and HLA-Cw6 − controls or patients, suggesting that LILRA3 has no role in psoriasis.

Four families of human in vitro cell lines were tested for minisatellite restriction fragment length polymorphism (RFLP) using multilocus probes MZ1.3 and/or 33.15 after digestion of DNA with restriction enzymes HinfI or HaeIII. These results confirmed that (i) the RFLP pattern is relatively stable in established cell lines and, therefore, could be used as a specific marker of a cell line identity, (ii) the use of MZ1.3 and 33.15 probes permits the identification of hybridomas and (iii) one of the cell lines tested, a lymphoblastoid cell line HAJ, may possess a hot spot of mutation.

The C3 and BF phenotype frequencies were studied in children with mumps meningitis. No significant differences were found between this group and other groups; children with mumps without meningitis and healthy children.

The Fc receptor for immunoglobulin A (IgA), FcalphaRI, is expressed on several types of myeloid cells, and activates them upon ligand binding. However, binding of IgA to the extracellular domain of the receptor requires previous stimulation of the cell by cytokines, and the cytoplasmic tail of FcalphaRI has been shown to play a role in this. Therefore, polymorphism in this region might affect this process. However, no changes in the amino acid sequence in this region of the FcalphaRI have so far been reported. Here, we describe for the first time a single nucleotide polymorphism in exon 5 of the immunoglobulin A Fc receptor (FCAR) gene leading to a Ser-->Gly substitution at position 248 of the mature FcalphaRI protein. Prediction of structural features suggests some changes that may affect the function of the protein to some extent. However, the Gly248 variant is quite common (4% homozygotes and 38% heterozygotes) in healthy population, suggesting a weak effect, if any, on function, at least in heterozygotes.

Psoriasis vulgaris, particularly its juvenile form, is strongly associated with the HLA-Cw*06 allele encoding the HLA-Cw6 molecule. This molecule is recognized by the inhibitory receptor KIR2DL1 and the activatory receptor KIR2DS1, which are expressed on natural killer cells and subpopulations of T lymphocytes. Humans differ by the presence or absence of particular KIR genes. We hypothesized that either activatory KIR2DS1 or inhibitory KIR2DL1 gene frequencies might be different in psoriatic patients from a control population. Therefore, we compared the frequencies of KIR2D inhibitory (L) and activatory (S) genes in 116 psoriasis vulgaris patients and in 123 healthy controls. Fourteen novel gene combinations were found. KIR2DS1 was present in 85% of the patients, but only in 51% of the controls (corrected p [pc] < 0.0009). Similarly, HLA-Cw*06 was much more frequent in patients (77%) than in controls (17%; pc < 0.00002). Statistical analysis suggests that, although the contribution of these two factors to psoriasis is partially independent, they interact nevertheless. This result strongly speaks for a role of KIR2DS1 on recognition of HLA-Cw6 in susceptibility to psoriasis.

Association of psoriasis vulgaris with HLA-C is not equally strong in different human populations. It has not yet been studied in Polish patients at DNA level, but only by serology that is inadequate for HLA-C. Therefore, we examined the distribution of HLA-C alleles by means of low resolution PCR-SSP in 102 Polish psoriatics and 123 healthy controls. We have found significantly higher representation of HLA-Cw*06 (odds ratio, 18.73; P(cor)0.001) and significantly lower representation of HLA-Cw*07 (odds ratio, 0.41; P(cor)0.038) in patients than in controls. Association of HLA-Cw*06 with psoriasis was even stronger in early age at onset (0-20 years) group: odds ratio, 77.71; P(cor)0.001. Therefore, our population seems to belong to those with strong association of psoriasis with HLA-Cw*06.

Psoriasis vulgaris is a multifactorial disease; the strongest association was established with the HLA complex. The actual disease-predisposing gene(s) has not been identified yet, but several genes from this region were examined in addition to HLA-C and -B. However, HLA-linked complement component polymorphic genes were not extensively studied. Therefore, we typed 67 psoriatic patients for alleles of the HLA-linked complement components BF, C4A and C4B. Alleles of C3, encoded on another chromosome, were established in parallel as a negative control. Frequencies in patients were compared with those in unrelated healthy controls, 100 individuals for C4A and C4B, 890 for BF and 4719 for C3 We found no association of BF alleles with disease, similarly to C3. Among C4 alleles, C4B*3 was present in 13.4% of patients as compared with 1% of controls (OR, 15.36; 95% CI, 1.897-124.42; P=0.0009), and C4A*6 was present in 19.4% of patients versus 7% of controls (OR, 3.20; 95% CI, 1.202-8.508; P=0.0155). The high frequency of C4B*3 in psoriatics has not been described so far. These results suggest a contribution of C4 genes themselves or a closely linked gene to the susceptibility to psoriasis.

Human major histocompatibility complex class I antigens, HLA-C, are expressed on the cell surface at approximately a tenfold lower level than HLA-A and -B. We hypothesized that the expression of HLA-C is limited by the quantity of high affinity peptides which bind to these molecules, thus allowing only a small fraction of HLA-C molecules to be transported and/or to remain stable on the cell surface. If this assumption is correct, then the addition of exogenous peptide should increase cell surface HLA-C expression. To verify the hypothesis, we pulsed lymphoblastoid cell line PAJ (HLA-Cw3+) with synthetic HIV-1 p24gag 145-152 peptide, known to be presented to T-lymphocytes by HLA-Cw3 molecule. PAJ (HLA-Cw3+) cells bound approximately two times more of the peptide than HAJ (HLA-Cw3-), and four times more than 500/C9 (HLA-Cw3-) cells. Accordingly, overnight pulsing of PAJ cells with the p24gag 145-152 peptide caused an increase in class I HLA expression detected on the cell surface by flow cytofluorimetric analysis with anti-HLA-B,C monoclonal antibodies but not by anti-HLA-A antibody. In contrast, HLA-Cw3- cells treated in the same manner did not show any increase of HLA class I expression. Our data suggest that low concentration of high affinity peptides within the cell may be one of the factors limiting cell surface expression of HLA-C molecules.

Mixed connective tissue disease (MCTD) is a systemic autoimmune disease, originally defined as a connective tissue inflammatory syndrome with overlapping features of systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), polymyositis/dermatomyositis (PM/DM) and systemic sclerosis (SSc), characterized by the presence of antibodies against components of the U1 small nuclear ribonucleoprotein (U1snRNP). The aim of the study was to assess the frequency of (high-resolution-typed) DRB1 alleles in a cohort of Polish patients with MCTD (n = 103). Identification of the variants potentially associated with risk and protection was carried out by comparison with the DKMS Polish Bone Marrow Donor Registry (41306 alleles). DRB1*15:01 (odds ratio (OR): 6.06; 95% confidence interval (CI) 4.55-8.06), DRB1*04 (OR: 3.69; 95% CI 2.69-5.01) and *09:01 (OR: 8.12; 95% CI 2.15-21.75) were identified as risk alleles for MCTD, while HLA-DRB1*07:01 allele was found to be protective (OR: 0.50; 95% CI 0.28-0.83). The carrier frequency of the DRB1*01 was higher in MCTD patients compared with controls, although the differences were not statistically significant. Our results confirm the modulating influence of HLA-DRB1 genotypes on development of connective tissue diseases such as MCTD.