Sex differences in immune responses that underlie COVID 19 disease outcomes
There is increasing evidence that coronavirus disease 2019 (COVID 19) produces more severe symptoms and higher mortality among men than among women 1 5 However, whether immune responses against severe acute respiratory syndrome coronavirus (SARS CoV 2) differ between sexes, and whether such differences correlate with the sex difference in the disease course of COVID 19, is currently unknown. Here we examined sex differences in viral loads, SARS CoV 2 specific antibody titres, plasma cytokines and blood cell phenotyping in patients with moderate COVID 19 who had not received immunomodulatory medications. Male patients had higher plasma levels of innate immune cytokines such as IL 8 and IL 18 along with more robust induction of non classical monocytes. By contrast, female patients had more robust T cell activation than male patients during SARS CoV 2 infection. Notably, we found that a poor T cell response negatively correlated with patients' age and was associated with worse disease outcome in male patients, but not in female patients. By contrast, higher levels of innate immune cytokines were associated with worse disease progression in female patients, but not in male patients. These findings provide a possible explanation for the observed sex biases in COVID 19, and provide an important basis for the development of a sex based approach to the treatment and care of male and female patients with COVID 19. Male patients with COVID 19 have higher plasma levels of innate immune cytokines and chemokines such as IL 8, IL 18 and CCL5 and more non classical monocytes than female patients, whereas female patients mount robust T cell activation maintained even in older age.
Nature