Ultra low-dose IL-2 for GVHD prophylaxis after allogeneic hematopoietic stem cell transplantation mediates expansion of regulatory T cells without diminishing antiviral and antileukemic activity

PURPOSE

GVHD after allogeneic hematopoietic stem cell transplantation (alloSCT) has been associated with low numbers of circulating CD4(+)CD25(+)FoxP3(+) regulatory T cells (Tregs). Because Tregs express high levels of the interleukin (IL)-2 receptor, they may selectively expand in vivo in response to doses of IL-2 insufficient to stimulate T effector T-cell populations, thereby preventing GVHD.

EXPERIMENTAL DESIGN

We prospectively evaluated the effects of ultra low-dose (ULD) IL-2 injections on Treg recovery in pediatric patients after alloSCT and compared this recovery with Treg reconstitution post alloSCT in patients without IL-2. Sixteen recipients of related (n = 12) or unrelated (n = 4) donor grafts received ULD IL-2 post hematopoietic stem cell transplantation (HSCT; 100,000-200,000 IU/m(2) ×3 per week), starting <day 30 and continuing for 6 to 12 weeks.

RESULTS

No grade 3/4 toxicities were associated with ULD IL-2. CD4(+)CD25(+)FoxP3(+) Tregs increased from a mean of 4.8% (range, 0%-11.0%) pre IL-2 to 11.1% (range, 1.2%-31.1%) following therapy, with the greatest change occurring in the recipients of matched related donor (MRD) transplants. No IL-2 patients developed grade 2-4 acute GVHD (aGVHD), compared with 4 of 33 (12%) of the comparator group who did not receive IL-2. IL-2 recipients retained T cells reactive to viral and leukemia antigens, and in the MRD recipients, only 2 of 13 (15%) of the IL-2 patients developed viral infections versus 63% of the comparator group (P = 0.022).

CONCLUSIONS

Hence, ULD IL-2 is well tolerated, expands a Treg population in vivo, and may be associated with a lower incidence of viral infections and GVHD.

Screening for atrial fibrillation in patients aged 65 years or over attending annual flu vaccination clinics at a single general practice

BACKGROUND

Atrial fibrillation (AF) is a common, treatable cause of stroke. Screening is recommended at influenza vaccination ('flu') clinics, but not implemented nationally.

OBJECTIVES

We aimed to determine if screening for AF by pulse assessment of those aged ≥ 65 years attending flu vaccination is effective, practical and feasible. The success of screening was determined by discovery of undiagnosed cases, estimating the prevalence of undiagnosed AF, assessing the accuracy of a second-year General Practice Specialty Trainee (GPST2) and interpretative software at diagnosing AF on electrocardiography (ECG), completion without disrupting routine practice, estimating cost-effectiveness and guiding future screening.

DESIGN

Patients ≥ 65 years old attending flu clinics were screened. Patients with an irregular pulse had an ECG, with interpretation by the GPST2, interpretative automated software and a reporting service.

RESULTS

A total of 573 patients were screened, identifying 95 patients with an irregular pulse: 21 had prior AF, 5 were < 65 years old and 1 had a previous myocardial infarction (MI); 68 were invited for ECG, of whom 39 attended; 2 new cases of AF were diagnosed. Pre-screening AF prevalence was 12.2% in those aged ≥ 75 years, and 12.4% after screening. A new case was discovered for every 286 patients screened. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 100% for the GPST2 and interpretative software for ECG diagnosis of AF versus cardiological assessment. Identifying a new case cost approximately £234. Limitations included low uptake of ECG appointments, and delayed and low completion of ECGs, leading to missed AF diagnoses.

CONCLUSIONS

Screening was ineffective. ECG immediately after pulse assessment is essential. Screening was acceptable to patients but required additional resources. Age groups 65-74 and ≥ 85 years were not adequately screened using flu clinics. Novel methods screening older, non-attending patients are required. Practices should introduce annual pulse checks into chronic disease templates and prompts for those aged ≥ 65 years attending surgery. Additional screening should target practices with low AF prevalence or poor rates of opportunistic screening.

In vivo biodistribution of nanoparticles

Nanoparticles have potential applications in diagnostics, imaging, gene and drug delivery and other types of therapy. Iron oxide nanoparticles, gold nanoparticles and quantum dots have all generated substantial interest and their properties and applications have been thoroughly studied. Yet, metal-containing particles raise biodistribution and toxicity concerns because they can be quickly cleared from the blood by the reticuloendothelial system and can remain in organs, such as the liver and spleen, for prolonged periods of time. Design considerations, such as size, shape, surface coating and dosing, can be manipulated to prolong blood circulation and enhance treatment efficacy, but nonspecific distribution has thus far been unavoidable. Renal excretion of nanoparticles is possible and is size dependent, but the need to incorporate coatings to particles for increased circulation can hinder such excretion. Further long-term studies are needed because recent work has shown varying degrees of in vivo toxicity as well as varying levels of nanoparticle excretion over time. The interaction of these particles with immune cells and their effect on the innate and adaptive immune response also needs further characterization. Finally, more systematic in vitro approaches are needed to both guide in vivo work and better correlate nanoparticle properties to their biological effects.