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1.
M R Harris C S Kindle A F Abruzzini C W Pierce S E Cullen 《Journal of immunology (Baltimore, Md. : 1950)》1984,133(3):1202-1208
We examined the antigen-presenting capacity of BCL1 tumor cells, which are capable of differentiating in vitro with respect to immunoglobulin synthesis/secretion under the influence of LPS. In vivo passaged BCL1 cells depleted of host cell contamination either by positive selection employing panning with anti-lambda reagents, or by elimination of latex-ingesting adherent cells, are capable of MHC-restricted antigen presentation to a GAT-immune T cell line. The BCL1 cells act as antigen-presenting cells when freshly explanted, but gradual loss of this function occurs, and cells cultured for 3.5 days cannot present antigen unless LPS is included during the culture period. BCL1 cells are equivalently Ia+ after the culture period with or without LPS stimulation. Other B cell lines capable of antigen presentation appear to express this trait constitutively, and the in vivo passaged BCL1 line is therefore unique among B cell lines in having antigen-presenting cell function that can be modulated. The data suggest that freshly explanted or LPS-cultured BCL1 cells are heterogeneous with respect to antigen-presenting capacity, and the basis for this heterogeneity is being sought. BCL1 offers an opportunity to study requirements for antigen presentation by B cells. 相似文献
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Comparison of factor IX methylation on human active and inactive X chromosomes: implications for X inactivation and transcription of tissue-specific genes. 总被引:11,自引:2,他引:9 下载免费PDF全文
Maintenance of dosage compensation for housekeeping genes on the human X chromosome is mediated through differential methylation of clustered CpG nucleotides associated with these genes. To determine if methylation has a role in maintaining inactivity of X-linked genes which show tissue-specific expression, we examined the locus for blood clotting Factor IX. The analysis encompassed 91% of the HpaII and HhaI sites in the 41-kb region that includes the presumed promoter region, 5 kb of 5'- and 4 kb of 3'-flanking sequences. Although there are sex differences in methylation of the locus in leukocytes, the methylation pattern in liver, where the gene is expressed, is essentially the same for loci on the active and inactive X chromosome. The lack of differences in methylation of active and inactive genes makes it unlikely that methylation within the locus has a role in expression of the Factor IX gene. These findings, along with the absence of clustered CpG dinucleotides within the Factor IX locus, suggest that functional differences in DNA methylation related to X chromosome dosage compensation may be limited to CpG clusters. In any event, dosage compensation seems to be maintained regionally, rather than locus by locus. 相似文献
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We have further characterised our tissue culture system for the growth in vitro of Drosophila imaginal disc cells, including the culture medium requirements for optimum growth and we have adjusted the protocol recommended for the initiation of cultures. Many imaginal disc fragments become organised into vesicles, and some of these secrete extracellular material into the lumen. Sensory axons differentiate in primary disc cultures, in the absence of bristle formation. The early stages of cell division to form a cell line are recorded. 相似文献
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Dr. Patrick Chardon Marek Kirszenbaum Philippa R. Cullen Claudine Geffrotin Charles Auffray Jack L. Strominger Daniel Cohen Marcel Vaiman 《Immunogenetics》1985,22(4):349-358
Four cDNA probes for the human major histocompatibility complex (MHC) were used to investigate the sheep MHC, in conjunction with serological typing for ovine lymphocyte antigen (OLA). Lymphocytes from a family (two parents and five offspring) of Romanov sheep were subjected to genomic DNA digestion by the restriction endonuclease Eco RI, followed by gel electrophoresis. A single Southern blot representing all seven individuals was then consecutively hybridized with the class I, alpha-DC, beta-DR, and C4 probes, which were originally designed to identify HLA class I, class II (DC and DR), and C4 products, respectively. Using each of the three class I/class II probes, several bands showing DNA polymorphism were detected. The segregation of these bands in the five offspring exactly paralleled the OLA haplotype segregation established by serological typing. A further eight individuals carrying haplotypes which were phenotypically identical to those in the above-mentioned family showed bands in the corresponding positions when tested with the same three probes. Using the C4 probe, no polymorphism was detected in these fifteen individuals.Abbreviations used in this paper MHC
major histocompatibility complex
- OLA
ovine lymphocyte antigen
- kbp
kilobase pair(s)
- MLR
mixed lymphocyte reaction
- RFLP
restriction fragment length polymorphism 相似文献
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B R Cullen 《Cell》1986,46(7):973-982
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Our data demonstrate that the uptake of surface Ia into an intracellular compartment of B lymphoma or normal spleen cells is limited to about 20% after 2 to 3 h. The extent of internalization does not vary with several types of stimulation, including LPS, phorbol esters, anti-Ig-plus phorbol ester-stimulated EL-4 T cell supernatant, and Con A supernatant. Resting and activated B cells had similar rates of internalization. The rate and extent of uptake of surface Ia molecules into an intracellular compartment was monitored quantitatively through the use of a mAb radiolabeled with 125I. The internalization of Ia molecules was compared to that of transferrin receptor, a receptor that undergoes rapid internalization and recycling and accumulates in a intracellular pool that can be trapped by monensin. The internalization of Ia was not affected by monensin, although its synthetic pathway is disturbed by this drug. The potential use of internalized Ia for formation of T cell-triggering complexes of Ia and Ag fragments is not ruled out by these data, but it appears unlikely that internalization provides the major mechanism permitting Ia interaction with Ag. 相似文献
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