Cytokines for Immune Cell Culture

Immune cells encompass those involved in immune responses or related processes. This group includes Natural Killer (NK) Cells from the innate immune system, Dendritic Cells, Monocytes/Macrophages, Granulocytes and Mast cells, which are also part of the innate immune system, as well as B cells and T cells from the adaptive immune system^[1].

Recombinant cytokines and immune cell culture models constitute significant tools within immunological research and hold a crucial position in immune cell therapies. For example, in CAR-T cell therapy, recombinant cytokines can be used to repeatedly induce cell proliferation and differentiation, thereby facilitating the development and application of this therapeutic approach^[2].

Cytokines possess multiple advantages in the culture of immune cells:

• Maintenance of Cell Viability: Cytokines sustain the survival of immune cells and concurrently promote their activation and differentiation to reach the targeted phenotype.
• Optimization of Immune Cell Function In Vitro: Cytokines provide essential signals that promote the activation, proliferation, differentiation, and survival of immune cells, thereby enhancing their adaptability and activity within the in vitro environment.
• Standardization of Cell Culture Conditions: Recombinant cytokines exhibit features such as high purity, high biological activity, low endotoxin levels, and batch-to-batch consistency. By utilizing these cytokines, a standardized cell culture environment can be created, which reduces variability in experimental results and improves the reproducibility and reliability of experiments.

Cytokines for T cell culture and differentiation

The characteristic markers of T cell include the The characteristic markers of T cells include the T cell receptor (TCR) and cluster of differentiation (CD) molecules. Based on the expression of surface molecules, T cells can be broadly categorized into CD4⁺ T cells and CD8⁺ T cells. CD4⁺ T cells orchestrate the overall immune response by interacting with specialized antigen-presenting cells (APCs), whereas CD8⁺ T cells exhibit direct cytotoxicity against target cells. Antigen-specific T cells are activated in accordance with the expression of cell membrane molecules or secreted cytokines and effector molecules, and subsequently differentiate into effector cells^[3,4,5].

Cytokines for CD4⁺ T cell culture and differentiation

Cytokines for CD8⁺ T cell culture and differentiation

Cytokines for B cell culture and differentiation

B cells, or B lymphocytes, are a subtype of white blood cell known as lymphocytes. They are distinguished from other lymphocytes by the expression of B cell receptors (BCRs), which can can specifically bind to antigens and generate antibodies. Key processes in B cell activation and maturation include class switching, antibody production, and the regulation of cytokine secretion.

In the in vitro culture of B cells, recombinant cytokines facilitate B cell proliferation, activation, and differentiation. For example, IL-10, IL-4, and IL-2 can stimulate their differentiation into immunoglobulin (Ig)-secreting cells. Additionally, CD40 ligand (CD40L) promotes B cell proliferation, inducesimmunoglobulin class switching, and protects B cells from apoptosis by binding to the B cell receptor CD40^[6,7].

Cytokines for NK cell culture and differentiation

Natural killer (NK) cells are lymphocytes that belong to the innate immune system. Unlike other lymphocytes, including B cells, T cells, and natural killer T (NKT) cells, NK cells do not express antigen-specific receptors such as B cell receptors (BCR) or T cell receptors (TCR). Instead, they function antigen-independently, endowed with intrinsic cytotoxic potential and the capacity to produce cytokines. The phenotype of human NK cells subsets is characterized by high levels of NCAM-1/CD56 expression and the absence of CD3 expression (CD56⁺, CD3^-)^[8,9,10].

The activation, proliferation, survival, and effector functions of NK cells typically rely on a combination of different cytokines.

Cytokines for Monocyte/Macrophage cell culture and differentiation

Monocytes are the largest type of white blood cells and play an important role in the adaptive immune response. They typically circulate in the bloodstream for 1 to 3 days before migrating to tissues throughout the body, where they differentiate into macrophages and monocyte-derived dendritic cells. In the immune system, monocytes primarily perform functions such as phagocytosis, antigen presentation, and cytokine production^[11]. Human macrophages, derived from purified CD14⁺ monocytes are generally classified into two main categories based on their activation and function: M1 and M2.

Cultivation of monocytes in vitro requires various cytokines to maintain their survival, activate their differentiation, and promote their expansion into macrophages and their subtypes. For instance, the microbial component lipopolysaccharide (LPS) combined with IFN-gamma can drive macrophage polarization toward the M1 phenotype, while IL-4 can induce polarization toward the M2 phenotype. Several subsets of the M2 phenotype, commonly referred to as M2a, M2b, M2c, and M2d, are induced by different stimulating factors and exhibit distinct phenotypes and functions^[12,13,14].

Cytokines for Granulocyte cell culture and differentiation

Granulocytes are a type of white blood cell characterized by the presence of granules in their cytoplasm, and they are also known as polymorphonuclear leukocytes (PMNs or PMLs) due to the diverse morphology of their nuclei. Neutrophils, eosinophils, and basophils — the three types of granulocytes — are distinguished by their staining properties under Wright's stain^[15].The application of recombinant cytokines in culture can promote the activation and maturation of granulocytes. For example, IL-3 as an effective hematopoietic growth factor that is involved in the differentiation of bone marrow progenitor cells and the activation of basophils. IL-5 not only activates eosinophils but also exerts a synergistic effect with IL-3 and GM-CSF, thereby enhancing their development and maturation^[16].

Cytokines for Dendritic cell culture and differentiation

Dendritic cells (DCs) are a group of diverse hematopoietic cells that serve as a bridge between the innate and adaptive immune systems. Their principal function is the processing and presentation of antigens to T cells in the immune system, and they are currently recognized as the most effective APCs^[17]. Currently, methods for the culture and expansion of DCs from various sources, including bone marrow, circulating monocytes, and induced pluripotent stem cells (iPSCs) have been described. Regardless of the source, the in vitro culture, activation, and maturation of DCs require the synergistic action of various cytokines. For example, FLT-3 ligand, stem cell factor (SCF), and GM-CSF play a decisive role in the development of blood-derived DC subsets, including conventional DCs (cDCs) and plasmacytoid DCs (pDCs)^[18,19]

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