Subset-specific analysis of calcium fluxes in murine AIDS

Infection of susceptible strains of mice with the Duplan strain of murine leukemia viruses induces a syndrome called MAIDS (murine acquired immunodeficiency syndrome) characterized by immunodeficiency and lymphoproliferation, In addition to a complete refractoriness of most subsets of lymphocytes to mitogen stimulation, the development of phenotypic abnormalities occurs such as the appearance of an abnormal CD4(+) T cell subset lacking membrane Thy-1, This study was performed to compare the calcium responses during the early stages of MAIDS (week 9 or earlier) between T cells and B cells and between CD4(+)Thy-1(-) and CD4(+)Thy-1(+) T cells, B cells were strikingly less affected than T cells: their baseline [Ca2+](i) did not significantly increase, and their calcium response to anti-lgM antibody and concanavalin A (Con A) was partially maintained. In contrast, the response to Con A was completely abolished in T cells, Interestingly, calcium mobilization in response to membrane receptor-independent stimuli such as ionophores and thapsigargin was strongly inhibited in T cells, while no such inhibition was found in B cells, In comparison with their CD4(+)Thy-1(+) counterparts, CD4(+)Thy-1(-)T cells had blunted calcium responses in controls, as well as in infected mice, However, CD4(+)Thy-1(+) T cells were also strikingly altered, suggesting that the loss of membrane Thy-1 could be associated with, but not directly responsible for abnormalities of calcium responses in CD4(+) T cells from RadLV-Rs-infected mice.