SUBSET-SPECIFIC ANALYSIS OF CALCIUM FLUXES IN MURINE AIDS

Infection of susceptible strains of mice with the Duplan strain of mur ine leukemia viruses induces a syndrome called MAIDS (murine acquired immunodeficiency syndrome) characterized by immunodeficiency and lymph oproliferation, In addition to a complete refractoriness of most subse ts of lymphocytes to mitogen stimulation, the development of phenotypi c abnormalities occurs such as the appearance of an abnormal CD4(+) T cell subset lacking membrane Thy-1, This study was performed to compar e the calcium responses during the early stages of MAIDS (week 9 or ea rlier) 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 c alcium response to anti-lgM antibody and concanavalin A (Con A) was pa rtially 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 thapsi gargin was strongly inhibited in T cells, while no such inhibition was found in B cells, In comparison with their CD4(+)Thy-1(+) counterpart s, 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 s trikingly altered, suggesting that the loss of membrane Thy-1 could be associated with, but not directly responsible for abnormalities of ca lcium responses in CD4(+) T cells from RadLV-Rs-infected mice.