*3.1.7 NKT cells*

Is another type of cell in the lymphoid lineage that shares features with both conventional T lymphocytes and NK cells like T cells; NKT cells have T-cell receptors (TCRs) and some express CD4. Unlike most T cells, however, the TCRs of NKT cells are not very diverse and recognize specific lipids and glycolipids presented by a molecule related to the major histocompatibility complex (MHC) proteins called CD1.

Like their innate immune counterparts, NK cells, NKT cells have antibody receptors.

NKT cells are considered as a cell subset belonging to the innate immune system with the capacity to amplify adaptive immune responses in asthma [7–9, 21].

Defining the roles of thymic stromal lymphopoietin, IL-25, and IL-3 in human asthma:

IL-25, IL-33, and TLSP are epithelial-derived cytokines and have been identified as having an important role in asthma pathogenesis. These cytokines have been described as epithelial-derived alarmins that activate and potentiate the innate and humoral arms of the immune system in the presence of actual or perceived damage.

TSLP is increased in asthmatic airways, mast cells and in the lungs is produced mainly by airway epithelial cells. In addition, these three cytokines can generate a H2 cytokine profile independent of the adaptive immune system. TSLP is a

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*The Immunology of Asthma and Allergic Rhinitis DOI: http://dx.doi.org/10.5772/intechopen.86964*

of asthma [22–24].

*3.1.8 IL-33*

*3.1.9 IL-C2*

known as innate lymphoid cells.

regulation of inflammation.

(bronchioles) of the lungs.

Asthma [25].

antibodies.

*3.1.10 CC16 club cells/Clara cells*

and respiratory bronchioles of humans.

**3.2 The adaptive inflammatory cells**

(effector) and anti-inflammatory (regulatory) cells.

cells encompass an entity called the adaptive immune system.

TH2-promoting cytokine that significantly contributes to the immune pathogenesis

Interleukin-33 (IL-33), which belongs to the larger family of damage-associated

Innate lymphoid cells are a group of lymphoid cells with a recently recognized role as regulators of innate immunity, inflammation, and tissue repair at the barrier surfaces. They are a lymphoid subclass characterized by the lack of either B- or T-cell receptors but retain cytotoxic or immunomodulatory capacity [22–24].

The innate defense system contains cells that look just like B or T lymphocytes under the microscope, yet express neither B- nor T-cell receptors. These cells are

Innate lymphoid cells are classified into three groups based on their transcription factors and cytokine production patterns, which mirror helper T-cell subsets. Unlike T cells and B cells, ILCs do not have antigen receptors. They respond to innate factors released by the bronchial epithelium, such as cytokines and alarmins, including IL-33, IL-25, and thymic stromal lymphopoietin [22–24]. ILCs produce multiple pro-inflammatory and immune regulatory cytokines for the induction and

Clara cells are non-ciliated, non-mucous, secretory cells in respiratory epithelium. These epithelial cells secrete several distinctive proteins, including Clara cell 10-kDa secretory protein (CCSP). Clara cells are most predominant in the terminal

Club cells, also known as bronchiolar exocrine cells and originally known as Clara cells, are dome-shaped cells with short microvilli, found in the small airways

Of recent Clara cells (CC16) have re-emerged in the immune pathogenesis of

T-cell responses to antigens consist of a combination of pro-inflammatory

• Lymphocytes differentiate into separate lineages. The B lymphocytes secrete

The T lymphocytes operate in a supervising role to mediate cellular and humoral responses. Antigen presentation describes a vital immune process which is essential for T-cell immune response triggering immunity. B and T lymphocytes produce and express specific receptors for antigens. Collectively, the functions of the T and B

T-helper lymphocytes conventionally are TH1 and TH2 cells. TH1 cells produce

cytokines that downregulate the atopic response. In those who are genetically susceptible to developing asthma, antigen presentation to T-helper cells leads to a

molecular pattern molecules, has been considered as an "alarmin" [22–24]. It is released to alert the immune system by first-line cells, such as tissue epithelial cells. TH2-promoting cytokine that significantly contributes to the immune pathogenesis of asthma [22–24].
