key: cord-0927914-lw2zha79
authors: Cassius, C.; Merandet, M.; Frumholtz, L.; Bergerat, D.; Samri, A.; Grolleau, C.; Grzelak, L.; Schwartz, O.; Yatim, N.; Moghadam, P.; Jaume, L.; Bagot, M.; Legoff, J.; Delaugerre, C.; Bouaziz, J.‐D.; Le Buanec, H.
title: Analysis of T‐cell responses directed against the spike and/or membrane and/or nucleocapsid proteins in patients with chilblain‐like lesions during the COVID‐19 pandemic
date: 2021-09-07
journal: Br J Dermatol
DOI: 10.1111/bjd.20647
sha: aff3441988686eaa685c1c369dd9edbac7a4c728
doc_id: 927914
cord_uid: lw2zha79

A range of cutaneous manifestations has been described in association with severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) infection during the coronavirus disease 2019 (COVID-19) pandemic 1 . Among them, chilblain like lesions (CLL) occurred more frequently than expected. A direct link was demonstrated thanks to the visualization of viral particles in the skin endothelial cells by electron microscopy 2 which was further questioned 3 . An indirect link was highlighted with high prevalence of seropositivity in CLL patients compared to general population 4 .

spanning the SARS-CoV-2 spike, nucleocapsid and membrane protein (each at 2 mg mL À1 ; Miltenyi Biotec, Bisley, UK). The response was compared between patients with CLL, patients with RT-PCR-confirmed mild COVID-19, and healthy control samples collected before the pandemic. We detected reactive T-cell responses directed against the spike and/or membrane proteins and/or nucleocapsid in 33% of CLL, 31% of healthy control and 100% of COVID samples. The CLL samples had higher levels of spot-forming unit than healthy controls, although not significantly (median 23Á3, interquartile range 3Á3-98Á3 vs. À12Á2, interquartile range À21-170, P = 0Á37) ( Figure 1 ).

Although SARS-CoV-2 is known to elicit a strong antibody response towards both surface and nucleocapsid peptides during systemic and pulmonary severe and mild disease, little is known about the humoral response in asymptomatic patients. Moreover, specific T-cell response has been less studied, but it has recently been shown that when asymptomatic, patients more frequently display a T-cell response than a humoral response. 7 Given that chilblains are described as a later manifestation of COVID-19, 1 it is unsurprising that the patients had negative PCR results. Moreover, RT-PCR can give false negatives if the amount of viral genome is insufficient or if the correct time window of viral replication is missed. Discrepancies between studies concerning positive serologies, some reporting seropositivity in up to 30% of patients with CLL, 4 may be explained by many factors. Among them are different sensitivity, different timing between onset of disease and blood collection, and searching for only certain isotypes. Therefore, we used three different serology techniques to improve sensitivity, collected blood at two timepoints and searched for IgA anti-SARS-CoV-2 antibodies, as they have been shown to be associated with vasculitis manifestations. The S-Flow assay has the advantage of capturing all anti-SARS-CoV-2 S protein antibodies and providing excellent sensitivity. Nevertheless, none had a positive serology, consistently with previous reports. 5 We and others have previously demonstrated that the cellular infiltrate plays a key role in the pathogenesis of CLL, and more particularly type I IFN, T helper 1 polarization and cytotoxic infiltration, highlighting the role of the cellular response. 4 However, we demonstrate for the first time that patients with CLL have the same specific T-cell response towards either the S, N or M protein as healthy controls. This could be explained by a pre-existing cross-reactive CD4 T-cell memory towards common-cold coronaviruses, as described previously in up to 20-50% of people, or by the absence of a link between CLL and SARS-CoV-2. Further studies should be conducted studying specific CD4 and CD8 responses towards different peptides separately. For example, cross-reactivity with common-cold coronaviruses seems more important in the context of nucleocapsid-specific CD4 T cells. 8 Our data therefore do not demonstrate the role of SARS-CoV-2 in the pathogenesis of CLL through specific Tcell activation. 

Chilblains are a common cutaneous finding during the COVID-19 pandemic: a retrospective nationwide study from France

SARS-CoV-2 endothelial infection causes COVID-19 chilblains: histopathological, immunohistochemical and ultrastructural study of seven paediatric cases

SARS-CoV-2 has not been detected directly by electron microscopy in the endothelium of chilblain lesions

Clinical, laboratory, and interferon-alpha response characteristics of patients with chilblain-like lesions during the COVID-19 pandemic

Lack of association between chilblains outbreak and severe acute respiratory syndrome coronavirus 2: histologic and serologic findings from a new immunoassay

IgA dominates the early neutralizing antibody response to SARS-CoV-2

Robust T cell immunity in convalescent individuals with asymptomatic or mild COVID-19

SARS-CoV-2-specific T cell immunity in cases of COVID-19 and SARS, and uninfected controls

Acknowledgments: We thank all of the medical staff from the dermatology department of Saint-Louis Hospital, and particularly Drs Marie Jachiet, Antoine Petit and Anne Saussine. Our thanks also go to Marie-H el ene Durand, Elisabeth, Julie and Alain for their valuable assistance. We are also grateful to Drs Luc Sulimovic and Michel Rybojad and all members of the SNDV (French National Union of Dermatologists-Venereologists) (listed in Appendix S1; see Supporting Information). The authors gratefully acknowledge an equipment grant from Dormeur Investment Service Ltd, who provided funding to purchase the plate reader used here. 

Additional Supporting Information may be found in the online version of this article at the publisher's website:Appendix S1 Members of the French National Union of Dermatologists-Venereologists (SNDV) and member of Saint-Louis CORE.