Immune Cell Functions

Question 1

T helper cell 1 (TH1)

Answer 1

Cellular immune system. Maximizes the killing efficacy of the macrophages and the proliferation of cytotoxic CD8+ T cells. Also promotes the production of IgG, an opsonizing antibody. Interferon gamma (IFNγ) and TNF-β. Interleukin 2 and interleukin 10 production has been reported in activated Th1 cell.[25]

Question 2

T helper cell 2 (TH2)

Answer 2

Humoral immune system. Stimulates B-cells into proliferation, to induce B-cell antibody class switching, and to increase neutralizing antibody production (IgG, IgM and IgA as well as IgE antibodies). Interleukin 4, interleukin 5, interleukin 6, interleukin 9, interleukin 10, interleukin 13

Question 3

T helper 17 cells (Th17)

Answer 3

Th17 cells produce interleukin 17 (IL-17), a pro-inflammatory substance, as well as interleukins 21 and 22. This means that Th17 cells are especially good at fighting extracellular pathogens and fungi, particularly during mucocutaneous immunity against Candida spp.

Question 4

Regulatory T cells (Tregs)

Answer 4

Modulate the immune system, maintain tolerance to self-antigens, and prevent autoimmune disease. Treg cells are immunosuppressive and generally suppress or downregulate induction and proliferation of effector T cells. Treg cells express the biomarkers CD4, FOXP3, and CD25 and are thought to be derived from the same lineage as naïve CD4+ cells. Because effector T cells also express CD4 and CD25, Treg cells are very difficult to effectively discern from effector CD4+, making them difficult to study.

Question 5

Th22 cells (T helper cells type 22)

Answer 5

Through their production of interleukin-22 (IL-22), Th22 cells have been shown to be protective against a number of bacterial and viral pathogens. Interleukin-22 (IL-22) regulates different innate immune mechanisms to eliminate infiltration of invasive pathogens into the skin, gut and respiratory tract. Interleukin-22 (IL-22) influences keratinocytes and epithelial cells to stimulate proliferation and differentiation, thus promoting wound healing and cohesion of barrier integrity. Interleukin-22 (IL-22) also enhances stromal secretion of antimicrobial peptides, as well as production of the chemokines which promote recruitment of other immune cells.[7]

Question 6

T follicular helper cells (Tfh)

Answer 6

They play a critical role in protective immunity helping B cells produce antibody against foreign pathogens. Tfh are located in secondary lymphoid organs (SLOs), including the tonsil, spleen and lymph nodes.

Question 7

TH9 cells (T helper type 9 cells)

Answer 7

Play a role in defense against helminth infections, in allergic responses, in autoimmunity, and tumor suppression. The main physiological role of TH9 cells, while poorly defined, is defense against helminthic infections.This is likely mediated by local and/or systemic production of Interleukin-9, as well as promoted survival of other anti-parasitic leukocytes, including mast cells, eosinophils and basophils.

Th9 cells have also shown both pro- and anti-tumorigenic activity, depending on the type of cancer. They have been shown to inhibit melanoma cell growth, increase anti-tumor lymphocytes, and drastically lower tumor mass and disease severity. On the other hand patients suffering hepatocellular carcinoma with high TH9 infiltration had shorter disease-free survival period after surgical resection.