Vitamin D deficiency correlates with a reduced number of natural killer cells in intensive care unit (ICU) and non-ICU patients with COVID-19 pneumonia
Vassiliou et al.
, Vitamin D deficiency correlates with a reduced number of natural killer cells in intensive care unit (ICU) and..
, Hellenic Journal of Cardiology, doi:10.1016/j.hjc.2020.11.011
Observational study of 29 ICU patients and 10 non-ICU patients showing vitamin D levels positively correlated with cytotoxic T cells, natural killer (NK) cells, NK-T cells, and regulatory T cells.
Vassiliou et al., 9 Dec 2020, peer-reviewed, 11 authors.
Abstract: Hellenic Journal of Cardiology 62 (2021) 381e383
Contents lists available at ScienceDirect
Hellenic Journal of Cardiology
journal homepage: http://www.journals.elsevier.com/
Vitamin D deﬁciency correlates with a reduced number of natural
killer cells in intensive care unit (ICU) and non-ICU patients with
Natural killer cells
Regulation of immune function continues to be one of the most
well-recognised extra-skeletal actions of vitamin D. In vitro data
have shown that vitamin D modulates immune cells and induces
immune tolerance, while in vivo data from animal studies and
from vitamin D supplementation human studies have shown beneﬁcial effects of vitamin D on immune function, particularly in the
context of autoimmunity.1 In the present study, we examined
whether vitamin D deﬁciency modulates the number of immune
cells in COVID-19 patients.
This observational, single-centre study included consecutive
COVID-19 intensive care unit (ICU) patients (N ¼ 29) and consecutive patients hospitalised in a specialised non-ICU COVID-19 ward
(N ¼ 10) who were discharged from the hospital without being
transferred to the ICU, from March 18th 2020 to May 25th 2020.
The study was approved by the Hospital's Research Ethics Committee (129/19-3-2020), and all procedures carried out on patients
were in compliance with the Helsinki Declaration. Informed written consent was obtained from all patients or patients' next-ofkin. Total 25-hydroxyvitamin D was measured on hospital admission using the electrochemiluminescence immunoassay method
(Cobas E602, Roche Diagnostics International Ltd). Immune phenotyping was performed by ﬂow cytometric analysis (Navios EX ﬂow
cytometer, Beckman Coulter).
Vitamin D levels positively correlated with subpopulations of
immune cells, namely, cytotoxic T cells (rs ¼ 0.344, p ¼ 0.032), natural killer (NK) cells (rs ¼ 0.496, p ¼ 0.001), NK-T cells (rs ¼ 0.325,
p ¼ 0.044) and regulatory T cells (rs ¼ 0.333, p ¼ 0.038). With
respect to all other clinical and laboratory parameters, vitamin D
levels correlated only with albumin (rs ¼ 0.387, p ¼ 0.018). To
further explore these associations, we divided our cohort into
two groups based on their vitamin D levels; we classiﬁed them as
vitamin D deﬁcient (19.9 ng/ml, N ¼ 32) and vitamin D insufﬁcient (20-29.9 ng/ml, N ¼ 7). Demographics, clinical and biochemical characteristics on hospital admission and important outcomes
Peer review under responsibility of Hellenic Society of Cardiology.
of the two patient groups are listed in Table 1. As expected, hypertension was the most common comorbidity.2 The two groups
differed only in the number of NK cells (Table 1 and Figure 1). Cytotoxic T cells, NK-T cells and regulatory T cells did not differ in the
two groups. It should also be noted that the two patient groups
did not differ with respect to hospital mortality or disease severity.
The beneﬁcial effects of vitamin D on protective immunity are
due in part to its effects on the innate immune system. In vitro
studies have reported contradictory results on the role of vitamin
D on NK cell function, but whether vitamin D induces or inhibits
NK cell function in vivo remains unclear.3 NK cells are a type of
cytotoxic lymphocytes that are critical to the innate immune system and secrete many cytokines and chemokines. Despite their vital role in viral infections, the contribution of NK cells in..
Please send us corrections, updates, or comments. Vaccines and
treatments are complementary. All practical, effective, and safe means should
be used based on risk/benefit analysis. No treatment, vaccine, or intervention
is 100% available and effective for all current and future variants. We do not
provide medical advice. Before taking any medication, consult a qualified
physician who can provide personalized advice and details of risks and
benefits based on your medical history and situation. FLCCC
provide treatment protocols.