Recent Advances on Phagocytic B Cells in Teleost Fish

Abstract

The momentous discovery of phagocytic activity in teleost B cells has caused a dramatic paradigm shift from the belief that phagocytosis is performed mainly by professional phagocytes derived from common myeloid progenitor cells, such as macrophages/monocytes, neutrophils, and dendritic cells. Recent advances on phagocytic B cells and their microbicidal ability in teleost fish position B cells at the crossroads, bridging innate with adaptive immunity. Most importantly, an increasing body of experimental evidence demonstrates that, in both teleosts and mammals, phagocytic B cells can recognize, take up, and destroy particulate antigens and then present those processed antigens to CD4 + T cells to elicit adaptive immune responses and that the phagocytosis is mediated by pattern recognition receptors and involves multiple cytokines. Thus, current findings collectively indicate that teleost phagocytic B cells, as well as their counterpart mammalian B1-B cells, can be considered one kind of professional phagocyte. The aim of this review is to summarize recent advances regarding teleost phagocytic B cells, with a particular focus on the recognizing receptors and modulating mechanisms of phagocytic B cells and the process of antigen presentation for T-cell activation. We also attempt to provide new insights into the adaptive evolution of the teleost fish phagocytic B cell on the basis of its innate and adaptive roles.

Epidermal Club Cells in Fishes: A Case for Ecoimmunological Analysis

“…Indeed, B lymphocytes in teleosts have also been shown to function as antigen presenting cells [ 125 , 126 ]. The phagocytic ability of B lymphocytes is mostly studied, thus far, in context of IgM + B cell subsets [ 127 ]. In the absence of bone marrow in teleosts, progenitor B cells and plasma cells originate from and mature in the anterior (head) kidney and are activated in the posterior kidney or spleen [ 128 ].…”

Phytogenic Bioactive Compounds Shape Fish Mucosal Immunity

“…Interestingly, the phagocytic and bacterial-killing abilities of B cells in fish have been fairly introduced in the past (33). However, their antigen presentation mechanisms mediated by MHC II and costimulatory molecules (CD80/CD86 and CD83) to prime naïve CD4 + T-cells, produce IgM, IgT, and eventually IgD plasmablasts -a major lymphocyte population in the gut, gill and at some extent the skin-, have just been recently addressed (34,35). The IgT, the teleost specialized mucosal immunoglobulin analogous to mammalian IgA (36), plays a critical role in the clearance of mucosal pathogens and the preservation of microbiota homeostasis through immune exclusion (11).…”

Ecological Risks Due to Immunotoxicological Effects on Aquatic Organisms

“…A biological defense mechanism common to fish is the secretion of antibacterial proteins from the epidermis and digestive tract [ 89 ]. Phagocytic cells such as macrophages and neutrophils, NK cells, cytokines, MHC class I and II, T cells, and B cells are all found in fish and amphibians [ 88 , 90 ]. In both fish and many amphibians, the thymus and spleen serve as central and terminal lymphoid organs involved in lymphocyte maturation, but fish and amphibians do not have the lymph nodes and lymphoid bone marrow found in humans [ 91 ].…”