Malaria infection has long been associated with diminished T cell responses in vitro and more recently in experimental studies in vivo. Suppression of T cell-proliferative responses during malaria has been attributed to macrophages in a variety of murine and human systems. More recently, however, attention has been directed at the role of dendritic cells in this phenomenon, with several studies suggesting that maturation of dendritic cells is inhibited in vitro by the presence of malaria-infected E. In the studies reported here, we have examined the function of dendritic cells taken directly from infected mice. We found that they express high levels of costimulatory proteins and class II MHC, can activate naive T cells to produce IL-2 as efficiently as dendritic cells from uninfected mice, and support high levels of IFN-γ production by naive T cells through an IL-12-dependent mechanism. Dendritic cells from infected mice also support higher levels of TNF-α production by naive T cells. These same dendritic cells present parasite Ag to a malaria-specific T cell hybridoma, a finding that demonstrates that dendritic cells participate in the generation of Ag-specific immunity during infection. Our findings challenge the contention that dendritic cell function is inhibited by malaria infection.

The significance of mastocytaemia in cats is different from that in dogs because it appears exclusively associated with mast cell neoplasia. The prevalence of mastocytaemia was 0.05% of all feline submissions to a private laboratory and 43% in cats with mast cell neoplasia. None of 30 healthy cats had mastocytaemia. There was no sex bias or significant age difference between mastocytaemic and non-mastocytaemic cats with mast cell tumours (MCT). Buffy coat (BC) examination was the best screening method for detection of mastocytaemia but direct blood film examination was more accurate for quantifying degree of mastocytaemia. BC examination should be performed in all cases of suspected/known mast cell neoplasia as mastocytaemia was missed on nearly 30% of occasions when direct film examination only was used. Mastocytaemia was associated with decreased haematocrit (HCT) but not with other haematological parameters. Mastocytaemic cats can survive significant lengths of time (up to 27 months) even when splenectomy is not performed.