In vitro evidence for T‐B lymphocyte collaboration in the clawed toad, Xenopus

Abstract

Requirements for an in vitro secondary antibody response to the soluble antigens dinitrophenylated keyhole limpet hemocyanin and dinitrophenylated flow gamma-globulin are described for the clawed toad, Xenopus. Priming of both hapten and carrier-specific cells is required in order to obtain good responses to the hapten. The carrier-reactive ("helper") cells do not adhere to nylon wool, are X ray-resistant and surface Ig-negative. The cell adherence and X ray sensitivity characteristics of these Xenopus "T" cells and their ability to generate a mixed lymphocyte response, allogeneic cytotoxic and helper activities, are identical to those of thymus-derived (T) cells in higher vertebrates. The hapten-reactive, antibody-secreting cell precursors are nylon-adherent, X ray-sensitive and surface Ig-positive. In the absence of other distinguishing serological markers for T cells in frogs, and considering the thymus dependency of the helper activity described here, the evidence presented is interpreted as demonstrating the requirement for antigen-specific T-B cell cooperation in response to soluble protein antigens in vitro for Xenopus.

Immune Defenses againstBatrachochytrium dendrobatidis, a Fungus Linked to Global Amphibian Declines, in the South African Clawed Frog,Xenopus laevis

“…Experimental immunization of X. laevis induced the production of high-titer antibody responses of both the IgM and the IgY classes. Although we have not yet shown the T-cell contribution to this response, it is well known that the development of high-titer IgM and class-switched IgY responses in X. laevis requires T-cell help (5,62). Thus, the high-titer responses to B. dendrobatidis suggest that T cells are also being activated by this immunization.…”

Xenopus-FV3 host-pathogen interactions and immune evasion

“…Although, direct evidence of an anti-FV3 CD4 + T helper cell response is lacking, the role of CD4 + T cells in Xenopus antiviral response can be inferred by an expansion and infiltration of T cells recognized by the pan T cell marker CD5 that are CD8 negative, and by the production of effective IgY anti-FV3 antibodies able to inactivate FV3 in vitro (Chinchar and Waltzek, 2014; Maniero et al, 2006; Robert et al, 2005). The production of IgY antibodies requires T cell help (likely CD4 + ) for the isotype switch from IgM (Blomberg et al, 1980). Interestingly, as in the case of anti-pox immune response in mammals (Panchanathan et al, 2006, 2008), detectable potent IgY antibody response to FV3 in Xenopus only occurs during a secondary FV3 infection, despite the induced expression of the B cell specific activation-induced cytidine deaminase (AID) mediating isotype switch as early as 3 days following primary FV3 infection (Marr et al, 2007).…”

Defects in Host Immune Function in Tree Frogs with Chronic Chytridiomycosis

“…Although recent progress has been made in understanding aspects of resistance to Bd , the mechanisms of immunity appear complex and much remains unknown. The post-metamorphic amphibian immune system is fundamentally similar to that of mammals, demonstrating innate and adaptive responses including specific cell-mediated and antibody responses, and immunoglobulin isotype heterogeneity [16]–[19]. Innate host defense mechanisms, such as antimicrobial skin peptides and symbiotic bacteria, may influence susceptibility to Bd infection [20], [21].…”