Human Vγ9Vδ2 T lymphocytes recognize nonpeptidic products (phosphoantigens) of the MVA and DOXP pathways. This antigenic recognition requires presence of both the Vγ9 and the Vδ2 TCR chain and is present only (as far as we know) in Homo sapiens and non-human primates. Clearly, the recognition of the same phosphoantigens (e.g., isopentenyl pyrophosphate or 3-formyl-1-butyl-pyrophosphate) by γδ T cells is absent in rodents. The scientific basis of this absence is unknown. Nevertheless, based on our immunological knowledge, one can speculate that [complete the sentence and assess (based on your immunological knowledge) the hypothetic scenarios (53-61) as either incorrect (= "false") or potentially factually correct (= "true")]:
53. the absence of this interesting lymphocyte reactivity in rodents could be due to the possibility that the recognition of the given phosphoantigens is important for immunosurveillance against pathogens that do not infect rodents; hence this reactivity did not confer a survival advantage and was lost during the phylogenetic evolution.
54. rodent γδ T cells may be capable of recognizing phosphoantigens, but the phosphoantigen- presentation molecule may be missing in rodents.
55. only the memory phosphoantigen-specific γδ T cells may be present in rodents, but not the effector phosphoantigen-specific γδ T cells.
56. rodent phosphoantigen-reactive T lymphocytes may be deleted during negative selection in the thymus.
57. rodent dendritic cells may not be able to process phosphoantigens.
58. rodent MHC molecules are different from primate MHC molecules and may not be able to present the given phosphoantigens.
59. rodent γδ T cells may be capable of recognizing phosphoantigens, but the relevant co- stimulatory molecule may be missing in rodents.
60. rodent phosphoantigen-reactive T lymphocytes may not be expanded during positive selection in the thymus.
61. rodents may be tolerant/unresponsive to phosphoantigens.