Table 2.
Changes in lymphocyte population in severe cases when compared to mild cases or healthy controls of COVID-19 disease
| S. no | Study | Location | Date of publication | Sample size | CD3 | CD4 T cells | CD8 T cells | T cell exhaustion | T cell activation | T helper subsets | T regs | B cells | NK cells | Remarks |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Wan et al. [26] | China | 12/02/2020 | 123 | – | ↓** | ↓* | – | – | – | – | ↓ | ↓ | T lymphocytes were more inhibited in severe patients |
| 2 | Diao et al. (Pre-print) [25] | China | 20/02/2020 | 522 Cases | ↓** | ↓** | ↓** | ↑* | – | – | – | – | – | Increased PD-1+ CD8+Cells & Tim-3+ CD4+ T cells in ICU patients |
| 3 | Zhou et al. [60] | Nanchang, China | 22/02/2020 | 17 | ↓* | ↓* | ↓ | – | – | – | – | – | – | Total lymphocyte count was associated with progression of disease |
| 4 | Zhang et al. (Pre-print) [35] | Wuhan, China | 27/02/2020 | 1334 | ↓ | – | ↓ | – | – | – | – | ↓ | ↓ | Checked cell counts on admission and 24 h prior to death. Low lymphocyte count on admission might indicate poor prognosis |
| 5 | Sun et al. [65] | Wuhan, China | 02/03/2020 | 8 | ↑ (2/8) | ↑ (4/8) | ↑ (1/8) | – | – | – | – | – | ↓ (4/8) | Increase in Total T cell count |
| 6 | Liu et al. [28] | Wuhan, China | 10/03/2020 | 69 | ↓ | ↓ | ↓ | – | – | – | – | ↓ | ↓ | Lymphocytopenia including all cell populations was observed in severe cases |
| 7 | Qin et al. [55] | Wuhan China | 12/03/2020 | 452 (44) | ↓* | ↓* | ↓ | – | ↓ | ↑Naïve ↓Memory | ↓* Both naïve and induced | ↓ | ↓* | Decrease in Treg population may add to hyperactive immune response |
| 8 | Wu et al. [29] | Wuhan China | 13/03/2020 | 201 |
↓** ↓*$ |
↓** ↓$ |
↓* ↓*$ |
– | – | – | – | – | – | Persistence and gradual increase in lymphocytes may be required for effective immunity against SARS-CoV-2 |
| 9 | Wang et al. [58] | Wuhan China | 16/03/2020 | 69 | ↓** | ↓ | ↓ | – | – | – | – | ↑ | – | Older patients or those with underlying comorbidities are at higher risk of death |
| 10 | Chen et al. [12] | Wuhan China | 27/03/2020 | 21 | ↓* | ↓ | ↑* | – | – | – |
↑*CD45RA ↓ CD45RO+ |
↓* | ↑ | Suppressed IFN-γ by T cell may be related to disease severity |
| 11 | Wang et al. [61] | China | 30/03/2020 | 60 | ↓*** | ↓* | ↓** | – | – | – | – | ↓* | ↓ | CD8 + T cells tend to be an independent predictor for COVID-19 severity and treatment efficiency |
| 12 | He et al. [37] | Wuhan China | 12/04/2020 | 204 | ↓*** | ↓*** | ↓*** | – | – | – | – | ↓*** | ↓*** | Level of T lymphocyte could be used as an indicator for prediction of severity and prognosis of patients with COVID-19 pneumonia |
| 13 | Liu et al. [27] | Wuhan, China | 18/04/2020 | 40 | ↓* | ↓ | ↓* | – | – | – | – | ↓ | ↓ | Kinetic difference in immune cells between severe and non-severe cases were observed |
| 14 | Ouyang et al. [38] | China | 20/04/2020 | 11 | ↓ | ↓ | ↓ | – | – | DEG of Th17 were downregulated | – | – | – | Decreased T cell proportion with down-regulated gene expression related to T cell activation and differentiation are responsible for disease severity |
| 15 | Evangelos et al. [53] | Greece | 21/04/2020 | 54 |
↓** CD45+ |
↓** CD45+ |
– | – | – | – | ↑ CD45+ | ↓ CD45+ | Also observed significant reduction in HLA-DR expression on monocytes that improved with IL-6 inhibitor by in-vitro study | |
| 16 | Wang et al. [64] | Wuhan China | 23/04/2020 | 65 | ↓*** |
↓*** + |
↓* |
↑* PD-1+ CD8+ &CD4+ ↑ Tim-3+ CD4+& CD8+ |
↑*** HLA-DR CD4+ ↑*** HLA-DR CD8+ |
– |
↓*** CD45RA+ |
↓** | ND | IFN-γ producing ability of T cells were increased. In addition, expression of DC subsets were studied |
#Indicates changes in severe cases when compared to healthy controls or reference range
$Indicated changes in non-survivors when compared with survivors, rest indicates changes in severe cases in comparison to mild cases of COVID-19
ND indicates no difference observed when compared to mild cases or healthy controls; *p < 0.05; **p < 0.01; ***p < 0.001