B lymphocytes from early vertebrates have potent phagocytic and microbicidal abilities.
The present paradigm dictates that phagocytosis is accomplished mainly by 'professional' phagocytes (such as macrophages and monocytes), whereas B cells lack phagocytic capabilities. Here we demonstrate that B cells from teleost fish have potent in vitro and in vivo phagocytic activities. Particle uptake by B cells induced activation of 'downstream' degradative pathways, leading to 'phagolysosome' formation and intracellular killing of ingested microbes. Those results indicate a previously unknown function for B cells in the innate immunity of these primitive animals. A considerable proportion of Xenopus laevis B cells were also phagocytic. Our findings support the idea that B cells evolved from an ancestral phagocytic cell type and provide an evolutionary framework for understanding the close relationship between mammalian B lymphocytes and macrophages.
Li
Jun
J
Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Barreda
Daniel R
DR
Zhang
Yong-An
YA
Boshra
Hani
H
Gelman
Andrew E
AE
Lapatra
Scott
S
Tort
Lluis
L
Sunyer
J Oriol
JO
D016980:Aeromonas hydrophila / Q000276:immunology; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology* / Q000382:microbiology* / Q000648:ultrastructure; D005075:Biological Evolution; D002397:Catfishes / Q000276:immunology* / Q000382:microbiology; D004926:Escherichia coli / Q000276:immunology; D015870:Gene Expression; D007075:Immunoglobulin M / Q000032:analysis; D007136:Immunoglobulins / Q000235:genetics; D017686:Oncorhynchus mykiss / Q000276:immunology* / Q000382:microbiology; D010587:Phagocytosis / Q000235:genetics / Q000276:immunology*; D011971:Receptors, Immunologic / Q000235:genetics; D014982:Xenopus laevis / Q000276:immunology
D007075:Immunoglobulin M; D007136:Immunoglobulins; D011971:Receptors, Immunologic