Table 5.
Effect of tuberculosis and diabetes on lymphocyte responses
| Cell type | Function during infection | Effect of tuberculosis | Effect of diabetes | References |
|---|---|---|---|---|
| T-helper 1 (Th1) cells | Cell-mediated immune response | ↑ Th1 | ↑ Th1 | 121,124–126,131 |
| Target intracellular pathogens | ↑ IFN-γ, TNF-α, IL-2, NO, LT-α | ↑ IFN-γ, IL-2, TNF-α | ||
| Microbial defence | ↑↓ IL-10 | ↑↓ IL-10 | ||
| Macrophage activation | ↓ NOx | |||
| CTL proliferation | ||||
| T-helper 2 (Th2) cells | Humoral immune response | ↑↓ Th2 | ↓ Th2 | 120,122,124,131 |
| Assist B cells | ↑ TGF-β | ↑↓ IL-10 | ||
| Ig isotype switching | ↑↓ IL4, IL-10 | ↓ IL-4 | ||
| Extracellular pathogen defence | ↓ IL-5 | |||
| Stimulate M2 | ||||
| Eosinophil activation | ||||
| Mast cell activation | ||||
| T-helper 17 (Th17) cells | Defence against fungi and extracellular bacteria | ↑ Th17 | ↑ Th17 | 124,125,127,128 |
| Enhance neutrophil response | ↑ TNF-α, IL-17, IL-22, CXCL9, CXCL10, CXCL11 | ↑ IL-17, IL-22 | ||
| Stimulate resident cells to secrete chemokines | ||||
| Recruit neutrophils and macrophages to sites of inflammation | ||||
| Regulatory T (Treg) cells | Suppress and regulate immune responses | ↑ Treg | ↓ Treg | 119,120,124,125 |
| Decrease immune-mediated damage | ↑ TGF-β | ↑ IFN-γ | ||
| Cytokines inhibit effector T cells and APC | ↑↓ IL-10 | ↑↓ IL-10 | ||
| Prevent pro-inflammatory cytokine secretion | ||||
| Cytotoxic T cells (CTL) | Lysis of infected cells | ↑ CTL | ↑ CTL | 121,157–159 |
| Targets viruses and intracellular bacteria | ↑ IFN-γ, TNF-α, perforin, granulysin | ↑ IFN-γ, TNF-α | ||
| Release of cytolytic granules | ||||
| Induce apoptosis of target cells | ||||
| B cells | Humoral immune response | ↑ B cells | ↑ B cells | 132–134 |
| Antibody production | ↑ IFN-γ, TNF-α, IL-6, IL-12, IgG, IgG1 | ↑ IFN-γ, TNF-α, IL-6, IL-12, IgG2c | ||
| Differentiation into plasma cells | ||||
| Antigen presentation to T cells | ↑↓ IL-4, IL-10 | ↑↓ IL-10 | ||
| Immune modulation | ↓ Ig production |
↑, increased; ↓, reduced; ↑↓, increased or reduced (conflicting evidence); APC, antigen-presenting cells; CXCL10, chemokine C-X-C motif ligand 10; CXCL11, chemokine C-X-C motif ligand 11; Ig, immunoglobulin; IL-2, interleukin-2; IFN-γ, interferon-γ; LT-α, lymphotoxin-α; NOx, mono-nitrogen oxides; TGF-β, transforming growth factor-β; TNF-α, tumour necrosis factor-α.