Neuroblastoma cell lines can have very low MHC Ag expression. The cell lines are insensitive to allo-killing by primed CTL, but are sensitive to non-MHC-restricted cytotoxicity. IFN-gamma increased ...class I expression, but the cells remained insensitive to CTL. Susceptibility to nonrestricted effectors was preserved. Class I+ glioma cell lines behaved similarly. The CTL resistance was localized to the recognition phase. Neuroblastoma lines did not form conjugates with primed T cells, but were lysed if they were coupled to the effectors via lectins. The levels of class I expression, and resistance to CTL, were constant over a range of IFN doses. HLA-A,B,C structure and distribution were studied more intensively on one cell line, CHP-100. HLA-A2 and -A3 were present on greater than or equal to 99% of the cells, in a unimodal distribution. After IFN treatment, the levels were similar to B cell controls. In two-dimensional gel electrophoresis, the molecules co-migrated with those of B cell controls. The defect may thus be in accessory proteins that are necessary for T cell recognition or binding, rather than in the structure or distribution of the HLA-A,B,C proteins.
Recombinant human interleukin 2 (rIL-2) drives the proliferation of the cloned murine T-helper line L2. The initial G1 activation occurs during the first 20 hr after stimulation, with DNA synthesis ...(S phase) beginning approximately 20 hr after rIL-2 stimulation. Three patterns of protein synthesis were observed during G1 activation. Type I proteins (e.g., p72 and p66) were synthesized at near maximal rates as early as 4 hr after stimulation, with little change in rates of synthesis through the G1 to S phase transition. Type II proteins (e.g., p52 and p36) were detectable early after stimulation, but their rates of synthesis continued to increase throughout G1 activation, becoming maximal 24-28 hr after stimulation. Type III proteins (e.g., p93, p89, and p63) were synthesized maximally 4 or 8 hr after rIL-2 stimulation, then their rates of synthesis declined markedly to prestimulation levels. Type II proteins, p52 and p36, were shown to be correlated with cell proliferation, since their rates of synthesis were maximal while L2 cells were proliferating and declined as the cells returned to a quiescent state. The potassium channel blocker quinine inhibited cell growth and the synthesis of p52 and p36 when added 0 or 2 hr after rIL-2 stimulation but not when added 6 hr after rIL-2 stimulation. Thus, a quinine-sensitive event occurring in L2 cells between 2 and 6 hr after rIL-2 stimulation is necessary for synthesis of type II proteins, DNA synthesis, and cell proliferation.
Multiple major histocompatibility complex (MHC) alleles exist at most class I and II loci. Polymorphism of MHC polypeptides may reflect either different levels of selective pressure operating on each ...molecule or different mutation rates at different loci. To gain further insight into this issue, we sequenced the non-coding promoter region of the HLA-DRA gene from several Epstein-Barr virus-transformed B cell lines and compared the extent of polymorphism found in this region with the known polymorphism of the HLA-DQB promoter. Our results indicate that the HLA-DRA promoter displays a low level of polymorphism while the promoter of HLA-DQB exhibits a nucleotide substitution rate fivefold greater than that of DRA. Moreover, through phylogenetic analysis, the HLA-DRA promoter was found to have diverged much less than the associated alleles of HLA-DRB1 and -DQA1. Taken together, these results suggest that the HLA-DRA promoter is highly conserved and may be under a stronger functional constraint than the promoter regions of other MHC class II genes.
Ninety-nine infants from multiple gestation births and weighing < or = 1500 g at birth were matched with infants from single births to clarify the relationship of multiple gestation to retinopathy of ...prematurity (ROP). There was no significant difference in the incidence of ROP between the twins and the singletons (relative risk RR = 0.84, 95% confidence intervals CI = 0.61, 1.16). Logistic regression analysis confirmed that very low birth weight (VLBW), not single or multiple gestation, was the most significant predictor of ROP occurrence in either group. In 27 pairs of twin siblings from the original twin group, where both weighed < or = 1500 g at birth, we found that the second-born twin seemed at higher risk for developing ROP, but logistic regression showed that the lower birth weight of the second twin, not birth order, was the more significant predictor of ROP. These results indicate that ROP screening in VLBW twins may be conducted according to the same standard protocols as for singletons.
HLA‐C*04:112 differs from HLA‐C*04:01:01:01 by one nucleotide at position 270 resulting in an amino acid change, Lysine to Asparagine, at codon 66 of exon 2.
HLA‐A*23:50 differs from HLA‐A*23:01:01 by one nucleotide at position 112 resulting in an amino acid change, Arginine to Tryptophan, at codon 14 of exon 2.
Transfusion-associated graft-versus-host disease (TAGVHD) is a rare and usually fatal complication of blood transfusion which can arise when immunocompetent lymphocytes from the donor of a cellular ...blood product are transfused into a severely immunocompromised recipient. We describe the case of an 8-month-old male with a severe combined immunodeficiency syndrome who developed TAGVHD after receiving an unirradiated transfusion. Serologic HLA typing of the parents, the patient, and the blood donor demonstrated the foreign origin of circulating lymphocytes, confirming the diagnosis of TAGVHD. The manifestations of TAGVHD did not respond to medical immunosuppressive therapy, and bone marrow transplantation was planned to treat the underlying immunodeficiency as well as the TAGVHD. By using DNA-based class I and class II HLA typing, the child's HLA type was determined from nonhematopoietic tissues. This information proved critical in selecting the bone marrow donor. The child received immunosuppression, myeloablation, and a T-depleted, maternal bone marrow graft mismatched at one HLA class II allele. Trilineage hematopoietic engraftment occurred within 3 weeks, and the child remains clinically stable with no evidence of TAGVHD more than 2 years after the transplant. This case illustrates that TAGVHD can be successfully treated by allogeneic bone marrow transplantation and that DNA-based HLA typing can play a unique role in the diagnosis and management of TAGVHD.
A versatile method that allows efficient detection and selection of both transient and stable transfectants expressing exogenous cell-surface molecules is described and used to generate stable HeLa ...transfectants expressing each of the human HLA class-II isotypes, specifically the DR1, DQw8 and DPw2 heterodimers. The method combines use of the strong mammalian expression vector, CDM8, and a highly efficient transfection protocol with the powerful technique of immunomagnetic selection. It offers significant advantages in comparison to standard procedures involving co-selection with drug-resistance markers. The transfection efficiency can be assessed 60 h after transfection rather than after three weeks of drug selection. Repeated rounds of immunomagnetic selection applied over the subsequent ten days result in homogeneous populations which express the surface marker of interest stably at high levels, making further subcloning or fluorescence-activated cell sorting unnecessary. Any number of surface products can be transfected into the same cell, the only limitation being the availability of specific monoclonal antibodies (a DP/DR double transfectant is described expressing four exogenous gene products simultaneously). The high sensitivity of immunomagnetic selection and its applicability to large samples allows rescue of transfectants present at very low frequencies. Finally, the technique can be used as a coselection procedure, by analogy with drug coselection, to achieve expression even of non-cell surface products.
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