1,721,305 research outputs found
Characterization of murine newborn inhibitory T lymphocytes: functional and phenotypic comparison with an adult T cell subset activated in vitro by alphafetoprotein.
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1,25(0H)2D3 and TPA may induce select differentiation pathways in the HL60 promyelocytic cell line.
No full textMonocytic features can be induced in the myeloid cell line HL60 in order to provide a suitable in vitro model for the investigation of in vitro activity in mononuclear phagocytes. 1,25-Dihydroxyvitamin D3 (calcitriol) induced the HL60 cell line to express the monocytic differentiation antigen Leu M3 in about 30-50% of the cells along with an increase (up to 20%) in the expression of HLA-DR but not HLA-DQ class II antigen. Functional investigation showed that calcitriol-treated cells formed rosettes with sheep erythrocytes coated with an anti-sheep erythrocyte-specific IgG2a mouse MoAb and readily ingested them. In addition, these same sensitized erythrocytes were lysed in an 18-hr antibody-dependent cellular cytotoxicity (ADCC) assay. All together these data indicate the presence of functionally active Fc-IgG receptors (FcR). Sorting experiments demonstrated that only Leu M3+ HLA-DR+ cells contained the effector cell population; such was also the case for blood monocytes. This phenotypic profile was, however, not predictive per se of FcR presence and function, as 12,O-tetradecanoylphorbol-13-acetate (TPA)-induced HL60 cells neither formed rosettes nor phagocytosed nor exhibited ADCC activity, although they express Leu M3 and HLA-DR (as well as HLA-DQ) antigens. These results suggest that calcitriol and TPA cause the differentiation of HL60 cells along distinct pathways. On the other hand, different subpopulations with given predetermined differentiation capabilities may coexist in HL60 cell line. This hypothesis gains support by the observation that when TPA and calcitriol were added together to the undifferentiated cells, the resulting phenotypic pattern was representative of the different activities of both of the inducers as they were used separately
Identification of distinct lymphocyte subsets responding to subcellular fractions of Mycobacterium bovis bacille calmette-Guerin (BCG)
Full text linkIn order to investigate the ability of Mycobacterium bovis BCG vaccination to induce immune responses toward different classes of mycobacterial antigens and the cell populations involved in such responses, proliferation of distinct human lymphocyte subsets from BCG-vaccinated donors in response to different subcellular fractions of BCG was analysed and compared with that of not sensitized subjects. Proliferation of different cell subsets was evaluated by flow cytometric determination of bromodeoxyuridine incorporated into DNA of dividing cells and simultaneous identification of cell surface markers. Although a certain degree of variability was observed among different donors, after 6 days of in vitro stimulation BCG-vaccinated subjects displayed, as a mean, a stronger blastogenic response to all the classes of antigens compared with non-sensitized ones. PPD, culture filtrates and membrane antigens induced a predominant proliferation of CD4(+) T cells. In contrast, preparations enriched in cytosolic antigens elicited strong proliferation of gamma delta(+) T cells which, as a mean, represented 55% of the proliferating cells. Although to a lesser extent, proliferation of gamma delta(+) T cells was also elicited by preparations enriched in membrane and cell wall antigens. In response to the latter preparation proliferation of CD4(+) T cells and CD16(+)/CD3(-) (natural killer (NK)) cells was observed, as well. In particular, cell wall antigens were found to induce significantly higher levels of proliferation of NK cells compared with all the other classes of antigens
T-cell receptor BJ gene segment expression in human umbilical cord blood CD4 + and CD8 + T-cell subsets
No full textBy employing RT-PCR-based technology, followed by Southern-blot analysis, patterns of relative TRC BJ gene segment usage in human CD4+ and CD8+ umbilical cord blood T cells (UCT) from ten children were determined in relation to seven recombined TCR BV gene (sub) families (BV 3, 5S1, 6S1-3, 8, 9, 12 and 18). Normal frequency of usage of individual BJ members was observed to be extremely nonrandom. BJ usage in association with each BV was ranked and mean ranking values were calculated for individual BJs. Moreover, BJ family usage and family ranges as well as individual BJ over-representations were determined. In all these aspects of BJ exon expression, CD4+ and CD8+ UCT displayed similar distribution patterns. Comparisons of BJ usage in UCT subpopulations and in the adult peripheral blood lymphocyte (PBL) counterparts were performed and many similarities were observed. However, discrepancies in two parameters were recorded; contrary to observations in PBL, individual BJ over-representations were virtually absent in UCT, and significantly less wide BJ family ranges were demonstrated in CD8+ UCT relative to CD8+ PBL T cells. These differences support the notion that UCT are in a less dynamic state than are PBL T cells. Hence, despite the fact that PBL T cells are subjected to continuous antigenic challenge, the striking resemblance of PBL and UCT with regard to the overall individual relative usage, ranking, mean ranking and family utilisation of BJ gene segments, irrespective of the choice of recombined BV exons, may suggest a relatively nondiscriminatory role for the BJ gene product in antigen recognition as compared to those encoded by the BV, (N) and BD gene segments
Different Percentages of Peripheral Blood gamma-delta+ T Cells in Healthy Individuals from Different Areas of the World
No full textThe frequency of gamma delta(+) T cells in the peripheral blood of 26 Turkish, 24 Swedish, 35 Japanese and 14 'Asian' (non-Japanese) healthy blood donors and healthy volunteers were investigated by flow cytometry. In the Turkish group, 9.3% (median value) of the: CD3(+) peripheral blood T cells expressed the gamma delta T cell receptor. A similar level of gamma delta(+) T cells was found in the non-Japanese 'Asian' healthy volunteers (9.2%), while significantly lower values were detected in the Swedish (4.2%) and Japanese (4.5%) groups. These dramatic differences in normally occurring gamma delta(+) T cells in different groups of healthy individuals were further reflected by a low incidence of > 10% gamma delta(+) T cells in the Swedish (0/24) and Japanese (6/35) groups compared to the Turkish (12/26) and 'Asian' (5/14) groups. The described gamma delta(+) T cell differences between distinct ethnic groups are thus likely to be a consequence of environmental factors, but additional genetic influences cannot be ruled out. The present study demonstrates the potential importance of the ethnic origin and environmental history of subjects examined in studies of gamma delta(+) T cells-disease relations
T-cell receptor J-beta gene segment usage in immature and mature human thymocytes
No full textImmature double positive (DP, CD4+CD8+) and mature single positive (SP, CD4+CD8- and CD4-CD8+) human thymocytes from nine thymi were analysed for their complete patterns of relative TCR J beta multigene member usage in relation to six rearranged V beta family exons (V beta 5.1, 6.1-3, 8, 9, 12 and 18). Each sample tested contained mRNA transcripts corresponding to all potential V beta(D beta)J beta combinations. Individual J beta gene segments were expressed in a similar, highly non-random manner both in SP and DP thymocytes, irrespective of original genomic position of the individual associated V beta exon. In addition, ranges of family usage and frequency of individual over-representations of J beta gene segments, as determined in DP and SP thymocyte populations, displayed no significant differences. Upon comparison of DP and SP thymocytes, however, a discrepancy in one aspect of J beta gene utilization was established: decreasing J beta family 1/J beta family 2 ratios were determined to be positively correlated with increasing maturity of thymocytes, a condition further supported by data previously obtained from studies of PBL T cells. At the individual J beta gene level, the observed gradual modification of the relative family usage can largely be explained by a significant shift from a higher J beta 1.1/J beta 2.7 ratio in DP to a higher J beta 2.7/J beta 1.1 ratio in SP thymocytes. Altogether, the present results imply that selectional processes in the thymus appear to have only minor consequences on the distribution pattern of expressed J beta exons. Hence, the disproportionate pattern of TCR J beta gene usage seems to be established mainly at the recombinatorial level followed by minor adjustments during thymic and post-thymic events
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