The immunologic response to severe acute respiratory syndrome coronavirus 2.

Background: The spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has precipitated the worst global pandemic in a century, which has caused millions of infections and deaths as well as massive economic repercussions. Objective: As with any pathogenic virus, it is crucial to understand its unique interactions with the human immune system so that pharmaceutical and prophylactic interventions can be deployed to effectively control the pandemic. Methods: A literature search by using PubMed was conducted in 2020 with variants of the terms "COVID-19," "SARS-CoV-2," and "immunological response." English language articles that presented original data about the immunologic response to coronavirus disease 2019 (COVID-19) were selected for review. This article reviewed the current understanding of the innate and adaptive immune responses to SARS-CoV-2 infection, including their relationship to current therapeutic and diagnostic strategies. Results: SARS-CoV-2 uses several unique molecular techniques to evade detection by the innate immune system early in the course of infection, and upregulation of these innate immune pathways may possibly accelerate the time to recovery and prevent severe disease. Although the majority of cases results in the patients' recovery, a significant proportion of infections result in deaths prompted by the host's inflammatory overreaction to the infection, a response that can be attenuated with corticosteroids and potentially other immune modulators. Conclusion: Current work by the scientific community to further understand how SARS-CoV-2 interacts with the human immune system will be invaluable to our response and preparedness for future coronavirus pandemics.

Automated red blood cell exchange for acute drug removal in a patient with sirolimus toxicity.

Sirolimus is an immunosuppressant used to prevent graft versus host disease in allogeneic hematopoietic stem cell transplant recipients. It has a large volume of distribution (12 ± 7.5 l/kg) and within the intravascular space ∼95% of it is bound to red blood cells. Because of potential toxic effects at high trough levels, therapeutic drug monitoring is recommended for sirolimus. We present a case of severe hepatic dysfunction due to Hepatitis B and sirolimus toxicity, in a 51-year-old male stem cell transplant recipient. An automated red cell exchange decreased his blood sirolimus level from 22.6 to 10.3 ng/ml (55% reduction) and improved his liver enzymes. Re-equilibration of sirolimus from other compartments to the blood necessitated a series of four red cell exchanges, after which the sirolimus level was 4.7 ng/ml. Although the patient ultimately succumbed to multiorgan failure, red cell exchange may be considered for acute removal of sirolimus in selected patients.