Wednesday , March 3 2021

the immune system that causes frostbite?

Frostbite is characterized by red or purple fingers, sometimes with small blisters, most often as a reaction to cold. These attacks, benign but particularly painful, occurred in many patients with Covid-19.

To illustrate this, physicians from CHU de Nice monitored patients admitted to the Covid cell between April 9 and April 17. Among them, 40 patients suffered from frostbite.

No more severe forms of Covid-19 have been reported. “If everyone was in contact or suspected of being infected with SARS-CoV-2 in the 3 weeks prior to counseling, the nasopharyngeal virus (PCR) virus test result was negative for all of them. These patients, and positive serology was found only in a third of them, ”Inserma scientists say in detail.

Nothing confirms that Covid-19 alone is responsible for these frostbites. But this causality is “nevertheless strongly doubted, especially because the number of patients who have frostbite at this time of year is particularly surprising,” details Professor Thierry Passeron *.

“In addition, we noticed groups of cases: several people suffer from frostbite in several siblings or families at the same time. “

Preactive immunity

Could the occurrence of these frostbites be the result of overly active immunity to SARS-CoV-2? To answer this question, the researchers compared the activity of innate immune cells (IFNα), from 3 groups of patients: “those who had frostbite, those who developed other non-serious forms of Covid-19, and those hospitalized for this infection.” .

As a result, “cells of the former show much higher levels of IFN expression than those of the other two groups. The rates measured in the cells of hospitalized patients, with severe forms of Covid-19, are even particularly low.

* Indoor Unit 1065 / University of Nice Sophia Antipolis, Mediterranean Center for Molecular Medicine, Department of Nice and Dermatology, CHU Nice, France

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