Differential Anatomical Expression of Transplantation Antigens Within the Normal Human Placental Chorionic Villus*

ABSTRACT: The expression of transplantation antigens by cells of the placenta was examined by immunohistological and immunoprecipitation procedures with defined conventional and monoclonal antisera to beta₂-microglobulin, DR and DC gene products, and H-Y antigen. Cells of the mesenchymal stroma within chorionic villi were positive by immunofluorescence for major histocompatibility complex antigens, and in male pregnancies for H-Y antigen, but the trophoblast was consistently negative for all antigen systems examined. Immunohistological examination of viable suspensions of cultured diploid trophoblast and of isolated membranes also gave negative results, and after radioiodination and solubilization of membranes, no detectable radioactive material was immunoprecipitated. These results provide further evidence that transplantation antigens are not expressed by human trophoblast. Since this is a fetal structure exposed directly to immunologically competent cells of the mother in the intervillous spaces, this observation may be relevant to the apparent lack of damaging maternal immune responses directed against the fetal homograft.     

Autoantibodies against the common antigenic determinant of group a streptococcal polysaccharide and epithelial cells of mammalian thymus and skin

A cross-reacting (CR) antigen, group A streptococcal polysaccharide and antigen of mammalian thymus and skin, was studied. The CR antigen was found in all adult human and embryonic tissues regardless of blood group, in all animals of different species studied, and in the tissues of rabbits immunized with streptococci and producing antibodies against A-polysaccharide. The results indicate that antibodies developing against the CR-determinant of A-polysaccharide and epithelial tissues belong to the class of autoantibodies. The reaction of these autoantibodies with the CR antigen is probably one cause of the development of autoimmune thymitis in rheumatic fever.Laboratory of Streptococcal Infections, N. F. Gamaleya Institute of Epidemiology and Microbiology, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR O. V. Baroyan.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 5, pp. 570–572, May, 1976.     

Expression of Haemophilus influenzae type b idiotype 1 on naturally acquired antibodies

The Chinese population in Hong Kong has a low incidence of invasive Haemophilus influenzae type b (Hib) disease, as well as carriage of the microorganism. Likely stimuli for the natural antibodies to Hib, which might protect against Hib infection, are cross-reactive antigens of bacteria like Escherichia coli K100. Our aim was to determine the isotype and idiotype distribution and cross-reactivity of natural antibodies against Hib capsular polysaccharide (CP) in healthy Hong Kong Chinese. Titration of 20 sera by ELISA showed IgG antibodies reacting with Hib CP in all individuals. The antibodies were mainly IgG2, and their avidity index ranged widely. Isoelectric focusing (IEF) combined with immunoblotting showed patterns of IgG2 antibody clones against the CP of Hib and E. coli K100 which were similar in 10 cases. Absorption with Hib CP only eliminated some bands in two sera. Absorption with K100 CP did not remove any anti-Hib CP bands. In three sera additional clones of antibodies reacting to K100 CP only, disappeared after absorption with this CP. Spectrotypic analyses of IgG antibodies reacting with anti-Hib idiotype 1 (Id-1) revealed stronger IEF patterns with bands in differing locations compared with anti-Hib CP antibodies. The strong reactivity of serum IgG, IgA and IgM antibodies with monoclonal anti-Hib Id-1 was confirmed by ELISA. This reactivity was not abolished after absorption of the sera with either Hib CP, or K100 CP. The data indicate a high prevalence of Id-1 among Hong Kong Chinese. However, only one individual had Id-1 antibodies specific for Hib CP, judging from absorption experiments. Others had much lower activity of Id-1 anti-Hib CP antibodies compared with the total IgG Id-1, suggesting that Hong Kong subjects have Id-1-positive antibodies in their serum which are not specific for Hib CP. This is consistent with the nature of Id-1, which is a marker of A2V_L region usage rather than a marker of a Hib CP paratope. We suggest that natural antibodies reacting with Hib CP in healthy Hong Kong Chinese are the product of exposure to some cross-reactive antigen(s), different from both Hib and E. coli K100 CP.     

人类白细胞抗原-G突变体cDNA克隆及在K562细胞上的表达

目的：克隆人类白细胞抗原-G(Human leukocyte antligen-G，HLA-G)突变体cDNA，并使其在HLA-I类阴性的K562细胞上获得稳定表达，为研究配-受体之间的识别机制奠定基础。方法：用RT-PCR方法从人子宫蜕膜组织扩增出HLA-GcDNA，得到全长HLA-GPCR产物后，用桥式PCR方法进行定点点突变，将突变的目的基因亚克隆于逆转录，将突变的目的基因亚克隆于逆转录mG-pLNCX表达载体，采用感染的方法将重组质粒转入K562细胞，最后经G418筛选及有限稀释，利用单克隆抗体W6/32进行FACS及mRNA检测，观察HLA-G突变体在靶细胞表面的表达。结果：HLA-G突变体分子在经mG-pLNCX转染的靶细胞表面获得稳定高表达。结论：成功构建了mG-pLNCX表达载体，并使HLA-G突变体分子在HLA-I类阴性的靶细胞K562细胞上获得稳定表达。     

Ultrastructural myeloperoxidase activity and expression of myeloid-associated antigens in acute lymphoblastic leukemia

Ultrastructural myeloperoxidase (MPO) activity and myeloid-associated antigen (MyAg) expression were investigated in 12 adult patients with acute lymphoblastic leukemia (ALL). Ultrastructural MPO was detected by 3 different methods. Immunophenotyping was performed by flow cytometry, using a series of monoclonal antibodies. Ultrastructural MPO-positive blast cells were detected in 6 patients (50%). In 5 of these 6 patients, the methods detecting both MPO and platelet peroxidase (PPO) activities found MPO-positive blast cells more frequently than those detecting MPO activity alone. In 2 patients (17%), at least one kind of MyAg was positive. Ultrastructural MPO activity was detected more frequently than MyAg expression in ALL patients. This method of detecting PPO and MPO is recommended for detection of ultrastructural MPO-positive ALL.     

Sequence of a novel HLA-A*0301 intronic variant (A*03010103)

We report here the full-length sequence of a novel HLA-A*0301 allele, A*03010103, which differs from A*03010101 by a single nucleotide substitution (G>T) at position 492 within intron 2. The variant was originally identified by Reference Strand-mediated Conformational Analysis (RSCA) and was confirmed by cloning and sequencing. The difference in RSCA mobility between A*03010101 and A*03010103 demonstrates the sensitivity of RSCA to detect single nucleotide polymorphisms.     

Influence of age and HLA type on interferon-gamma (IFN-gamma) responses to a naturally occurring polymorphic epitope of Plasmodium falciparum liver stage antigen-1 (LSA-1)

Antigenic polymorphism and HLA restriction may limit the immunogenicity of a subunit vaccine against liver-stage Plasmodium falciparum. We examined 59 clinical isolates and five laboratory clones of P. falciparum for polymorphism in the N- and C-terminal regions of LSA-1, evaluated binding of the corresponding peptides to selected HLA class I alleles, and measured IFN-gamma responses in residents of a malaria-endemic area of Papua New Guinea where HLA-A*1101, -24, -B13, and -B40 are the most common class I alleles. LSA-1 polymorphism was limited to a single non-synonymous mutation encoding serine (S), proline (P), or threonine (T) at amino acid 85. Nine-mer 84-92 peptides with S, T, or P at the primary anchor position bound differentially to HLA-A11, -A2, and -B7. IFN-gamma ELISPOT responses increased with age in malaria-exposed subjects: 14-16% and 30-36% of 2-5- and 6-54-year-olds, respectively, had > or =10 IFN-gamma-secreting cells/106 peripheral blood mononuclear cells when stimulated with at least one peptide variant (P<0.05). IFN-gamma responses to all three peptides were also greater for older than younger individuals. No children < 3 years old had lymphocytes that responded to all three 84-92 peptides, whereas 45% of adults (mean age 48 years) had aggregated IFN-gamma responses. These data support the notion that age-related cumulative exposure to P. falciparum increases the frequency of IFN-gamma responses to polymorphic epitopes of liver-stage antigens such as LSA-1.