Identification of T‐cell stimulating antigens from Giardia lamblia by using Giardia‐specific T‐cell hybridomas

Abstract

T-cell immune response plays an important role in controlling Giardia lamblia infections. Little is known about the G. lamblia-specific antigens that stimulate a cell-mediated immune response. The aim of the present study was to identify T-cell stimulating G. lamblia antigens. For this purpose, we generated a group of Giardia-specific T-cell hybridomas (2F9, 4D5, 6D10, 8B9, 9B10, 10F7 and 10G5). Hybridomas were screened for reactivity with G. lamblia protein extract by the CTLL bioassay. These T-cell hybridomas did not exhibit any significant activation either in the absence of G. lamblia protein extract or in the presence of irrelevant antigen (hen white egg lysozyme). To further characterize the T-cell hybridomas generated, we selected three hybridomas (10G5, 4D5 and 9B10). Giardia lamblia proteins of 90-110, 65-77 and 40-64 kDa showed T-cell stimulating activity for the hybridomas 10G5, 4D5 and 9B10, respectively, in a concentration-dependent manner. Protein extract obtained from different G. lamblia strains (GS/M-83-H7, WB C6 and a clinical isolate (YJJ)) stimulated all T-cell hybridomas, indicating that T-cell-stimulating antigens are expressed among different G. lamblia strains. In conclusion, we identified T-cell stimulating G. lamblia antigens by using Giardia-specific T-cell hybridomas. To our knowledge, these hybridomas are the first-described T-cell hybridomas specific for G. lamblia.

Giardia lamblia binding immunoglobulin protein triggers maturation of dendritic cells via activation of TLR4‐MyD88‐p38 and ERK1/2 MAPKs

“…Our identification of a ~74‐kDa binding immunoglobulin protein, BiP, in the screening experiment using G. lamblia ‐infected mouse serum, confirmed its role as a Giardia antigen (Figures S1 and ) which had been previously identified . Precedent studies proposed the presence of a Giardia antigen of ~72 kDa based on western blot analysis using monoclonal Abs generated from Giardia ‐infected mice , and characterization of Giardia proteins of 65–77 kDa revealed that this fraction had T‐cell stimulatory activity for Giardia‐ specific T‐cell hybridoma . In addition to the 74‐kDa GlBiP protein, we identified three more immunoreactive proteins at 62, 30 and 25 kDa in Giardia extracts upon incubation with anti‐ G. lamblia murine Abs (Figure S1), which need to be identified in future experiments.…”

The Microbiota Contributes to CD8+T Cell Activation and Nutrient Malabsorption following Intestinal Infection with Giardia duodenalis

“…The relative abundances of T cell populations within the IEL, however, are unaltered throughout infection in our model. The proliferation of Giardia-specific CD4 ϩ T cells has been reported in mice and humans (37)(38)(39). Several studies have shown that CD4 ϩ T cells are necessary for clearance of Giardia infections, and recent data have suggested that interleukin-17 (IL-17) is a key cytokine in mediating this protective effect (reviewed in reference 40).…”

Human Cellular Immune Response Against Giardia lamblia 5 Years After Acute Giardiasis

“…With the assemblage-unspecific responses observed and the relatively crude antigens used in this study, the antigen components responsible for these responses are likely to be more preserved between assemblages. A previous study that used Giardia-specific T-cell hybridomas indicated that T-cell-stimulating antigens are expressed among different G. lamblia strains [37]. Further characterization and identification of the immunodominant proteins in trophozoite fractions could lead to several potential candidates for an assemblage-unspecific mucosal vaccine.…”