SUMMARYThe chemiluminescent characteristics of enriched (>95%) peripheral blood polymorphonuclear leukocyte populations (PMN) from normal and feline leukaemia virus (FeLV)-infected cats were investigated. FeLV-infected cats demonstrated a significantly lower (P < 0.001) PMN chemiluminescent response when compared to the response of normal age-matched controls. Normal PMN treated with FeLVinfected cat serum exhibited a depressed response in comparison to control cells. A titration of serum from infected cats supplemented with normal serum revealed a titratable suppression of chemiluminescence with increasing concentration of serum from the infected cats. However, PMN from FeLV-infected cats treated with normal serum displayed a slight increase in chemiluminescence over the same cells in autologous serum. The addition of inactivated FeLV to normal PMN caused a titratable decrease in chemiluminescence.
Polymorphonuclear leukocytes (PMN) from healthy, normal control cats and FeLV-infected cats were analyzed for differences in phagocytic capabilities. One week after experimental infection, PMNs from FeLV-infected cats exhibited a marked decrease in phagocytic function as determined by the luminol-dependent chemiluminescent response. Depressed PMN function was observed in these cats during the viremic stage of infection and subsequently remained depressed after the cessation of viremia. The data presented here suggest that while nonviremic cats are reported as clinically normal, they may in fact be exhibiting a suppressed PMN function.
Experimental infection with the Mt. Airy isolate of feline immunodeficiency virus (FIVMA), a lentivirus isolated from a domestic cat exhibiting signs of an immunodeficiency-like syndrome, results in transient lymphadenopathy, fever, stomatitis, enteritis, neurologic abnormalities, and immunosuppression. The effects of FIVMA infection on neutrophil and natural killer cell (NK) function were examined in vitro. Suppression of neutrophil chemiluminescence (CL) responses, as well as reduction in NK-mediated cytotoxicity were demonstrated. Neutrophil CL was decreased by 50% in infected cats when compared to control values. This loss of CL was present through 6 months after infection. In addition, NK-mediated cytotoxicity was approximately 50% less in FIVMA infected cats than in controls. Loss of innate immunity was paralleled with inversion in feline CD4/CD8 lymphocyte ratios and decreases in lymphocyte mitogenesis seen as early as 5 weeks after infection. These results suggest that FIVMA infection induces an immunodeficiency disorder in infected cats similar to that seen in human immunodeficiency virus infections.
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