Table 2.

Effects of T2DM on the immune system.

Total leukocytes	Their numbers are elevated, are larger and more granular, express diminished levels of antioxidant genes but elevated levels of pro-apoptotic and pro-inflammatory genes.
Innate immunity
Complement system	Attachment of C-type lectin proteins to mannose residues is decreased, lectin pathway is impaired, CD59 activity is reduced, MAC deposition in vascular walls is increased.
Dendritic cells (DCs)	Their numbers and activity are reduced.
Macrophages	Their cholesterol efflux is decreased, generate foam cells, have dysfunctional efferocytosis.
Neutrophils	Are activated, constitutively release NETs, produce high levels of MPO, ROS, and calprotectin (S100A8/A9), are more susceptible to apoptosis, their migration, phagocytosis and microbial killing are impaired.
NK cells	Their numbers are increased but are usually dysfunctional, express high levels of GLUT4 but decreased levels of NKG2D and NKp46, have reduced degranulation capacity, are more susceptible to apoptosis.
NKT cells	Their numbers are increased, produce high levels of IFN-γ, IL-4, and IL-17, express high levels of NKp30, NKG2D, and NKp44 but low levels of NKG2A and 158b.
Innate lymphoid cells (ILCs)	ILC1s are increased and produce high levels of IFN-γ.
Adaptive immunity
Humoral immunity (B cells)	Germinal centers are reduced, Ab production and isotype switching is defective, Abs become glycated, Abs fail to activate complement.
Cellular immunity (T-Cells)	Pathogen-specific Th17 cells are decresed, Th1 cells are elevated, have decreased expression of perforin, GrB and CD107a.

Ab, antibody; GLUT-4, glucose transporter type 4; GrB, granzyme B; IFN, interferon; IL, interleukin; MAC, membrane attack complex; MPO, Myeloperoxidase; NET, neutrophil extracellular traps; NKG2D, the natural killer group 2d; ROS, reactive oxygen species; Th, helper T cell.