Immunogenicity of the yeast recombinant p17/p24:Ty virus-like particles (p24-VLP) in healthy volunteers.

In this Phase I study, immunisation with the yeast-derived p24 virus-like particles Ty p24-VLP (3 x 100 or 3 x 500 micrograms subcutaneously) in 16 healthy male subjects elicited p24 antibody responses in 4 of 16 (25%) subjects. After a fourth, intramuscular, immunisation (500 micrograms), p24 antibody responses were detected in 11 of 15 (70%) subjects. In addition to p24 antibody responses, T cell proliferative responses were also observed, although no HLA restricted p24-specific cytotoxic T cell responses were detected.

Identification of conserved antigenic components for a cytotoxic T lymphocyte-inducing vaccine against malaria.

Several cellular and humoral mechanisms probably play a role in natural immunity to Plasmodium falciparum malaria, but the development of an effective vaccine has been impeded by uncertainty as to which antigens are targeted by protective immune responses. Experimental models of malaria have shown that cytotoxic T lymphocytes (CTL) which kill parasite-infected hepatocytes can provide complete protective immunity against certain species of Plasmodium in mice, and studies in The Gambia have provided indirect evidence that CTL play a protective role against P falciparum in humans. By using an HLA-based approach, termed reverse immunogenetics, we have previously identified peptide epitopes for CTL in liver-stage antigen-1 and the circumsporozoite protein of P falciparum.

The MHC E locus in macaques is polymorphic and is conserved between macaques and humans.

Although the functions of the molecules encoded by the classical MHC class I loci are well defined, no function has been ascribed to the molecules encoded by the non-classical MHC class I loci. To investigate the evolution and conservation of the non-classical loci, we cloned and sequenced HLA-E homologues in macaques. We isolated four E locus alleles from five rhesus monkeys and two E locus alleles from one cynomolgus monkey, which indicated that the E locus in macaques is polymorphic.

HIV-specific cytotoxic T-cells in HIV-exposed but uninfected Gambian women.

A crucial requirement in the rational design of a prophylactic vaccine against the human immunodeficiency virus (HIV) is to establish whether or not protective immunity can occur following natural infection. The immune response to HIV infection is characterized by very vigorous HIV-specific cytotoxic T-lymphocyte (CTL) activity. We have identified four HIV-1 and HIV-2 cross-reactive peptide epitopes, presented to CTL from HIV-infected Gambians by HLA-B35 (the most common Gambian class I HLA molecule).

Recognition of viral antigens at the cell surface.

There is now a very good understanding of the way in which epitope peptides are generated from virus proteins and how the peptides bind to the class I MHC molecules. This gives a framework in which to analyse the potentially protective cytotoxic T lymphocyte response in human immunodeficiency virus infection. A detailed understanding of the specificity of the responding T cells, the clonality of these T cells and the effects of virus variation on the CTL gives a possible explanation for the ultimate failure of the CTL response to control this virus infection.

Immunization of human HIV-seronegative volunteers with recombinant p17/p24:Ty virus-like particles elicits HIV-1 p24-specific cellular and humoral immune responses.

Objective: To evaluate the immune response to HIV-1 p24 generated in vivo by p17/p24:Ty virus-like particles (p17/p24:Ty-VLP) by examining the lymphoproliferative and antibody (Ab) responses to HIV-1 p24, as well as Gag-specific cytotoxic T lymphocytes (CTL), in HIV-seronegative volunteers immunized with hybrid p17/p24:Ty-VLP.

Design And Methods: Sixteen HIV-seronegative volunteers were immunized with p17/p24:Ty-VLP at two dose levels (100 or 500 micrograms) and monitored for the following 48 weeks for production of anti-p24 and anti-p17 Ab, in vitro lymphoproliferative responses to HIV-1 p24 and p17, and in vitro CTL responses to HIV-1 Gag.

Results: Twelve out of the 16 volunteers had significant p24-specific proliferative responses, with volunteers on the higher dose schedule exhibiting earlier proliferative responses than those on the lower dose schedule.

Cytotoxic T cells in HIV2 seropositive Gambians. Identification of a virus-specific MHC-restricted peptide epitope.

A preliminary study of gag-specific, MHC-restricted CD8+ CTL has been performed in nine Gambian patients infected with HIV2. Such CTL were present in at least 55% of patients in fresh peripheral blood mononuclear cells without the requirement for in vitro restimulation. We have identified a nonamer peptide from HIV2 gag that is recognized by CD8+ HLA-B53 CTL using an amino acid sequence motif predicted from analysis of endogenous peptides eluted from HLA-B53 molecules.

An antigen processing polymorphism revealed by HLA-B8-restricted cytotoxic T lymphocytes which does not correlate with TAP gene polymorphism.

In previous studies of antigen presentation through HLA-B27, we identified a healthy person whose lymphoblastoid cells do not present three B27-restricted viral epitopes to specific cytotoxic T lymphocytes (CTL), despite adequate cell surface expression of HLA-B2702 of normal sequence. Similar findings were observed in all members of his family sharing the HLA-A3-B2702 haplotype. The original donor, NW, carries HLA-B8 on his other class I haplotype, which his daughter, HW, has inherited.

HIV-specific cytotoxic T-cell activity in an HIV-exposed but uninfected infant.

The factors necessary for protective immunity against HIV-1 are unknown. Important information about these factors should come from study of people at high risk of HIV infection who have not apparently become infected. Among these are the estimated 60-85% of children who may be exposed in utero or perinatally to HIV-1 but do not become infected.

Cytotoxic T lymphocyte epitopes shared between HIV-1, HIV-2, and SIV.

A peptide epitope from the gag protein of SIV and from HIV-1 is described which is presented by a cynomolgus macaque MHC molecule and with HLA B14. Comparisons were drawn between recognition of this peptide and that of a second peptide defined in SIV and HIV-2 which has been reported to be presented by the rhesus macaque molecule MaMuA01 and HLA B53 respectively.

A sequence pattern for peptides presented to cytotoxic T lymphocytes by HLA B8 revealed by analysis of epitopes and eluted peptides.

HLA B8-restricted cytotoxic T lymphocytes (CTL) specific for influenza A virus were generated and shown to recognize the nucleoprotein (NP). The dominant epitope was mapped using recombinant vaccinia viruses that expressed fragments of the NP and then synthetic peptides based on the NP amino acid sequence. The peptide 380-393 was first identified and further refined; it was shown that the glutamic acid at position 380 was essential for recognition by CTL and that the nonamer 380-388 was the optimum peptide.

Adequacy of peritoneal dialysis.

The combined annual mortality and drop out rate for peritoneal dialysis (PD) patients is relatively uniform worldwide at approximately 35%. The level of PD therapy prescribed in clinical practice is largely empirical and typically consists of four 2-L exchanges daily. It might be speculated that the 35% annual attrition rate in PD may in part reflect under dialysis in some patients due to empirical rather than quantitative and individualized prescription of PD therapy.

The measured creatinine generation rate in CAPD suggests only 78% of prescribed dialysis is delivered.

The creatinine generation was measured (GCr) in 132 continuous ambulatory peritoneal dialysis (CAPD) patients from the product of total daily peritoneal plus renal creatinine clearance and plasma creatinine (CpCr) plus the product of estimated gut clearance of 0.036 L/kg/day and CpCr. The creatinine generation was also predicted (PGCr) from gender, age, and weight.

CAPD prescription in current clinical practice.

A total of 132 patients from 15 dialysis centers were studied. Analyses were made of each drained dialysate exchange over 24 hours to determine total peritoneal urea clearance (KpT, liters/day), and a 24-hour urine was collected to determine total renal urea clearance (KrT, liters/day) and the sum of KpT+KrT or KprT, liters/day. Body water volume (V, L) was estimated from gender and surface area, and daily fractional urea clearance (KprT/V) was calculated.

Molecular analysis of the association of HLA-B53 and resistance to severe malaria.

The protective association between the human leukocyte antigen HLA-B53 and severe malaria was investigated by sequencing of peptides eluted from this molecule followed by screening of candidate epitopes from pre-erythrocytic-stage antigens of Plasmodium falciparum in biochemical and cellular assays. Among malaria-immune Africans, HLA-B53-restricted cytotoxic T lymphocytes recognized a conserved nonamer peptide from liver-stage-specific antigen-1 (LSA-1), but no HLA-B53-restricted epitopes were identified in other antigens. These findings indicate a possible molecular basis for this HLA-disease association and support the candidacy of liver-stage-specific antigen-1 as a malaria vaccine component.

Identification of the nonamer peptide from influenza A matrix protein and the role of pockets of HLA-A2 in its recognition by cytotoxic T lymphocytes.

Influenza matrix peptide 58-66 is shown to be the optimal nonamer for binding to HLA-A2 and presentation to cytotoxic T lymphocytes (CTL). If titered out to 2 x 10(-10) - 4 x 10(-10) M in CTL-mediated lysis assays and to 3 x 10(-9) M in an HLA-A2 assembly-stabilization assay in cell lysates. The peptide was shown to make probable contacts with its carboxy terminus close to residue 116 in the floor of the cleft of HLA-A2, close to the F pocket.

A pharmacodynamic model of erythropoietin therapy for uremic anemia.

Fifty-seven patients receiving chronic high-flux hemodialysis began receiving recombinant alpha-human erythropoietin (rHuEPO). The mean initial rHuEPO dose used in 54 evaluable patients was 9963 +/- 4364 U/week; the final dose was 8972 +/- 4058 U/week. Treatment over a mean period of 154 +/- 40 days (84 to 224 days) resulted in an average increase in hematocrit from 24.

Enhanced peritoneal dialysis delivery with PD-PLUS.

We prospectively studied the effects of enhanced continuous ambulatory peritoneal dialysis (CAPD) on the normalized protein catabolic rate (NPCR) and Kprt/V of two patients with zero residual renal function and marginal or below minimal HCFA values on urea kinetic modeling (Kprt/V = 0.21). Predictable increases in NPCR (from 0.

Human immunodeficiency virus genetic variation that can escape cytotoxic T cell recognition.

In a longitudinal study of HIV seropositive patients, there were fluctuations in the specificity of cytotoxic T cells for the virus. This was matched by variability in proviral gag DNA epitope sequences in the lymphocytes of these patients. Some of these viral variants are not recognized by autologous T cells.

The influence of dialysis treatment modality on the decline of remaining renal function.

A retrospective investigation was undertaken in which the rate of decline of residual renal function (RRF), estimated from creatinine clearance, was compared in 55 continuous ambulatory peritoneal dialysis (CAPD) and 57 hemodialysis (HD) patients for whom a minimum of four (mean of 7.6) well-spaced historic measurements of residual clearance were available. Because of the intrinsic variability that attends such data, specialized nonlinear, growth curve statistical methods were employed.

Comparison of conductivity measured hematocrit to microhematocrit.

Two electrical conductivity methods of hematocrit (H) measurement, Coulter Counter (CCH) and lonometer (IH), were compared to the microhematocrit (MH) with two different anticoagulants, Li Heparin (Li) and EDTA. The results showed MH-Li is higher than MH-EDTA (mean difference 1.7 vol%).

Kinetics and quality assurance: prescription therapy through kinetic modeling.

With recent startling statistics showing an increase in mortality risk of dialysis patients in the United States compared to other countries, managers and practitioners have been motivated to carefully examine not only the dialysis prescription, but what is actually delivered to the patient. In October 1990, prior to ANNA's Clinical Concerns in Nephrology meetings in Cincinatti and San Antonio, attendants were invited to participate in an education session examining the monitoring and evaluation of prescription therapy for peritoneal and hemodialysis. The title of the session was "The Nurse's Role in Prescription Therapy--What Does it Really Mean?" The sponsor was Fresenius USA, Inc.