Journal of Clinical and Cellular Immunology
Open Access

Immune Priming: Overview and its Mechanism

Andrew K Godwin^{* *}Correspondence: Andrew K Godwin, Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, USA, Email:

Author info »

Description

Antigen-specific T helper cell precursors make their first encounter with an antigen during priming. It is necessary for T helper cells to engage with B cells and make antibodies. When antigen is delivered to antigen-specific naive cells in immunogenic form, priming occurs. The primed cells will then develop into effector cells or memory cells, which will be able to mount a stronger and faster response to future immunological threats. Dendritic cell antigen presentation is required for priming of naive T lymphocytes. When naive CD8 T cells are primed, they become cytotoxic T cells that may kill pathogeninfected cells directly. Depending on the nature of the signals they receive during priming, CD4 cells can evolve into a variety of effector cell types. CD4 effector activity can entail cytotoxicity, but it is most commonly associated with the production of a group of cytokines that instruct the target cell to respond in a specific way. Cross-priming is the process of a dendritic cell delivering an antigen from the exterior of the cell stimulating antigen-specific CD8+ cytotoxic T lymphocytes (CTLs). Immunogenic cross-presentation is another name for crosspriming. CTL priming against viruses and tumours is dependent on this mechanism.

Immune priming

Immune priming is a memory-like phenomenon that has been observed in animal invertebrates. An organism's ability to generate a better and faster secondary immune response to a disease that is damaging and to which it is likely to be exposed again is favorable evolutionarily. Immune memory in vertebrates is built on adaptive immune cells known as B and T lymphocytes, which offer a stronger and faster immune response when exposed with the same pathogen again. Invertebrates are thought to lack memory-like immunological activities due to their lack of adaptive immunity. However, evidence indicating intrinsic memory-like capabilities has been discovered in recent years. Different bug species are used as model organisms in invertebrate immunology. Immune priming experiments involve exposing the insect to a dead or sub lethal concentration of bacteria or microorganisms to induce the innate immune response. Following that, the researchers compare subsequent infections in primed and non-primed people to see if they mount a stronger or modified response.

Mechanism of immune priming

Immune priming study appears to suggest that the mechanism varies and is reliant on the type of insect species and microbe employed in a given experiment. This could be due to coevolution between the host and the disease. It is advantageous for every species to acquire a specialised defence against a pathogen that it encounters frequently. It has been demonstrated in an arthropod model, the red flour beetle Tribolium castaneum, that the route of infection is critical for the formation of defence mechanisms. Non-cellular processes such as the synthesis of antimicrobial peptides (AMPs), reactive oxygen species (ROS), and the activation of the prophenol oxidase cascade are used by insects to provide innate immunity. Haemocytes, a cellular component of insect innate defence, can remove pathogens through nodulation, encapsulation, or phagocytosis. The innate response during immune priming varies depending on the experimental setup, but it generally involves higher quantities of haemocytes and augmentation of humoral innate immune responses.

The transfer of parental immunological experience to offspring, known as trans-generational immune priming (TGIP), may aid offspring survival when confronted with the same pathogen. In vertebrates, a similar method of offspring protection against infections has long been researched, in which the transfer of maternal antibodies aids the newborn’s immune system in fighting an infection before it can function properly on its own. TGIP in invertebrates has been extensively investigated over the last two decades. The procedure utilized for a specific inquiry may have an impact on the experimental outcome. The infection process, the offspring's and parent's sexes, and the developmental stage are just a few of these variables.