Methods
Participants
Four cohorts of participants were recruited: the first group included 24
convalescent health care workers who had suffered from COVID-19 and not
required hospitalisation to determine whether disease severity makes a
difference to the generation of any autoantibodies. The second group
included 25 individuals who were currently on the intensive therapy unit
(ITU) diagnosed with COVID-19. The third group included 32 individuals
who were currently on the ITU but for a reason other than COVID-19 to
determine whether acute illness per se was associated with autoantibody
production. The fourth group included 35 individuals who had been
admitted to ITU with COVID-19 and had been discharged and their samples
were taken at 3-6 month review. This group explored persistence of any
potential antibodies.
Autoantibody assays
Autoantibodies were detected on serum samples using indirect
immunofluorescence. A spectrum of anti-neutrophil and organ specific
autoantibodies were tested as a broad screen using standard ISO15189
accredited clinical tests. The immunoglobulin isotype detected was IgG
with the exception of endomysial antibodies which are IgA. The full list
of assays, manufacturers and disease association are described in theSupplementary data but in short we undertook indirect
immunofluorescence on commercial pre-prepared slides to detect IgG
antibodies for adrenal, autoimmune encephalitis, anti-neutrophil (ANA),
anti-neutrophil cytoplasmic ANCA, cardiac, epidermal, islet cell, a
range of cerebellar (Purkinje cell) antibodies, smooth muscle,
mitochondrial, gastric parietal cell and skeletal muscle antibodies and
IgA endomysial antibodies. All samples were read by two experienced
clinical laboratory scientists for agreement. Data are largely
descriptive. Inter group comparison was made by Chi Square using
GraphPad Prism 9.
Ethical approval
For the acute cohort of ITU patient, surplus anonymised samples from
routine clinical testing were used and for the convalescent ITU patients
they were consented in clinic; ethical approval for these groups was
granted by the North West-Preston Research Committee (ref 20/NW/0240
IRAS Project ID: 282164). The health care worker cohort was a random
subgroup of COVID antibody positive patients from the COvid-19
COnvalescent immunity study (COCO) study approved by the London - Camden
& Kings Cross Research Ethics Committee reference 20/HRA/1817.