instruction:
In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.
question:
Context: To investigate the role of the anti-cellular immune response in the protection of rhesus macaques against infection with the simian immunodeficiency virus SIVmac. To determine the biological differences between SIV challenge stocks grown either on human T-cell lines or on monkey peripheral blood mononuclear cells (MPBMC).', 'A protective SIVmac split vaccine was administered to rhesus macaques and their anti-, B- and T-cell response monitored. Vaccinees and controls were challenged with SIVmac grown either on human or on monkey cells. The in vivo replication rate of, and the immune response to, the two viruses was compared.', 'Five rhesus macaques were immunized with a total of 2 mg each of purified SIVmac251/32H grown on the human C8166 T-cell line. The antibody and proliferative T-cell responses were evaluated by enzyme-linked immunosorbent assay and T-cell proliferation assay, respectively. Four protected animals and four controls were reboosted and challenged with MPBMC-grown SIVmac251 (SIVmac251/MPBMC). Cell-free virus load was determined by titration of plasma for SIV infectivity on C8166 cells and antigen with a core antigen capture assay.', 'Protection from virus challenge with C8166-grown SIVmac251/32H or SIVmac251/MPBMC did not correlate with anti-cellular antibodies or proliferative T-cell reactivities. Control animals infected with SIVmac251/MPBMC showed high persistent antigenaemia and high plasma virus titres. Both were absent in controls infected with complement C8166-grown SIVmac251/32H. Whereas the latter always seroconverted against the full panel of viral polypeptides, SIVmac251/MPBMC-infected animals showed a drastically decreased antibody response.\Question: Does protection of monkeys by a split vaccine against SIVmac depend upon biological properties of the challenge virus?
answer:
Neither the antibody nor the proliferative T-cell response to SIVmac correlates with protection from virus challenge. In contrast to SIVmac251/32H grown on C8166 cells, the MPBMC-grown challenge virus SIVmac251 appears to belong to the 'rapid-high' phenotype, possibly explaining the lack of protection against this SIV.

question:
Context: Galbeta1-4GlcNAcalpha2-6 sialyltransferase (ST6GalI) is an acute phase reactant whose release from cells can be induced by proinflammatory cytokines. Because patients with chronic renal failure have high circulating levels of proinflammatory cytokines, we hypothesized that patients on the renal transplant waiting list would have high circulating levels of ST6GalI, which might adversely affect post-transplant events.', 'Levels of ST6GalI were measured in the serum of 70 patients immediately before renal transplant; these were correlated with posttransplant events, such as delayed graft function and rejection.', 'The mean serum level of ST6GalI was significantly higher in the patients (3162+/-97 U) than in 19 controls (2569 +/- 125 U; P<0.003). Patients who required dialysis posttransplant for treatment of delayed graft function (n=20) had significantly higher levels of ST6GalI pretransplant (3735+/-228 U) than patients (n=50) who did not require dialysis (2933+/-83 U; P<0.0001). In a multivariate analysis the ST6GalI level and cold ischemic time were found to be independent risk factors for the development of delayed graft function.\Question: Do increased levels of GALbeta1-4GLCNACalpha2-6 sialyltransferase pretransplant predict delayed graft function in kidney transplant recipients?
answer:
ST6GalI levels are high in renal failure patients awaiting a renal transplant and may be a risk factor for the development of delayed graft function. The assessment and perhaps modulation of a potential transplant recipient's ST6GalI systemic level may be beneficial.

question:
Context: After allogeneic haematopoietic stem cell transplantation (SCT) the whole T-cell receptor (TCR) repertoire shows a markedly skewed pattern for 2-3 years. A small fraction of CD4+ T cells is represented by CD25+ regulatory lymphocytes (Treg), which play a crucial role in modulating peripheral tolerance. To investigate their ability to react to the massive antigenic stimulation generated in an allogeneic host, which could significantly affect their pattern of reconstitution, we analyzed the TCR repertoire of Treg after SCT, focusing on the degree of similarity to CD4+CD25- conventional T cells (Tconv).', 'We assessed the TCR Vbeta repertoire of Treg in ten patients who had received allogeneic SCT, by using complementarity determining region 3 (CDR3) spectratyping. We developed a new similarity score for the analysis. This score expresses the proportion of Vbeta with similar profile between Treg and Tconv.', 'For up to 3 years after SCT the repertoires of Treg and Tconv were characterized by several Vbeta with different profiles between the two cell subsets, while they were extremely similar in patients more than 3 years post-allografting (similarity score= 0.90 vs. 0.61). The differences observed early after SCT were mainly ascribable to Vbeta expressing an oligoclonal profile in Tconv but not in Treg.\Question: Does t-cell receptor repertoire usage after allografting differ between CD4+CD25+ regulatory T cells and their CD4+CD25- counterpart?
answer:
Our data show that the TCR repertoires of Treg and Tconv are significantly different early post-SCT, while they tend to become identical with full reconstitution. This difference could reflect either a discrepancy in the in vivo reactivity against common antigenic stimulations or be the result of different post-transplant ontogeny.