Clinical and Immunological Characteristics of Cats Affected by Feline Infectious Peritonitis

Abstract

A set of 180 hospitalized or outdoor feline patients was examined for the presence of antibodies to feline coronavirus (FeCoV) and clinical signs of feline infectious peritonitis (FIP). The numbers of serologically and clinically positive cats were 55 (30.6%) and 35, respectively. The effusive and noneffusive forms of FIP were diagnosed in 24 and 11 animals, respectively. The most apparent signs, irrespective of the form of infection, included anorexia, lethargy, ischemic mucosae, and undernutrition. Hematological and immunological profiles of 14 FIP patients were compared with those found in a control group of 36 clinically normal and FeCoV-negative animals. A significant increase in the number of neutrophilic granulocytes was observed in the FIP patients (FIV-/FeLVcats with effusive form) and a significant decrease in the number of lymphocytes were observed in the FIP patients. Eosinopenia was also found in patients affected by the effusive form. No alteration of the phagocytic activity (ingestion of particles, chemiluminiscence) due to FIP was demonstrable. The blastic transformation test (stimulation with Con A, PHA, or PWM) showed a marked decrease in the activity of lymphocytes in the FIP patients. Concentrations of immunoglobulins and circulating immune complexes were increased in the affected animals. The expression of the lymphocyte surface antigens CD4, CD5, CD8, and CD21 was studied in a selected subgroup of the patients using flow cytometry. The results indicate an impairment of the activity of the immune system due to FIP. Therefore, treatment of FIP with immunosuppressive drugs is considered inappropriate.

Shifts in circulating lymphocyte subsets in cats with feline infectious peritonitis (FIP): pathogenic role and diagnostic relevance

“…In contrast, the low T cell counts detected in catteries with high prevalence of FIP suggests that the decreased number of these cells might be involved in differences in disease susceptibility among cats. This hypothesis is supported by the results recorded in cats with FIP, which had extensive lymphopenia with decreased numbers within all the lymphocyte subsets, in agreement with previous reports on blood (Knotek et al, 2000) and on tissues, where advanced FIP lesions were found to have less CD4 þ lymphocytes than recent ones (Paltrinieri et al, 1998). Compared to controls, the percentage of CD5 þ þ CD21 þ cells was significantly lower in cats with FIP, while the percentage of CD4 þ þ CD8 þ cells was close to the percentage of CD5 þ cells.…”

“…However, the possibility that in FIP-affected cats the percentage of non-T-non-B lymphocytes increases cannot be excluded. These findings, together with previously reported defects of T cell function (Gunn-Moore et al, 1998;Knotek et al, 2000) might play an important role in the development of FIP.…”

“…In contrast, a Th1 cytokine response (Gunn-Moore et al, 1998), and a follicular hyperplasia in lymph nodes (Kipar et al, 1999) have been reported in cats resistant to the infection. Circulating lymphocyte subsets have been analysed only in few cats with FIP and strong individual variations have been reported (Knotek et al, 2000).…”

Hyposialylated α1-acid glycoprotein inhibits phagocytosis of feline neutrophils

“…Hyposialylation has been found to be specific in FIP, but not in clinically healthy, FCoV infected cats (Ceciliani et al, 2004;Paltrinieri et al, 2008). Although previous report, performed with methods different from those reported in this study, suggested that phagocytosis is not suppressed in cats wit FIP (Knotek et al, 2000), the hyposialylation of fAGP, which we found to down-regulate phagocytosis, may influence the clinical outcome of FCoV infection by inducing a failure of cellular responses to the virus. Macrophages and neutrophils are involved in FIP immunopathology, being the most abundant, while hardly effective, populations in pyogranulomatous lesions (Kipar et al, 1998;Paltrinieri et al, 1998).…”

Pathogen exposure in endangered island fox (Urocyon littoralis) populations: Implications for conservation management

“…The presence of FeLV p27 antigen was detected by microtiter plate ELISA (IDEXX PetChek Ò , IDEXX, Portland, ME, USA) and results classified as positive (including equivocal) or negative (Lutz et al, 1983). Although foxes were not tested for FIV, FeLV and FCoV/FIPV, as these disease agents are feline-specific, these pathogens may compromise immunity in infected cats (Hoover and Mullins, 1991;Knotek et al, 2000;Pedersen and Barlough, 1991), making cats more susceptible to opportunistic infections with other disease agents (such as CDV, FPLV, FCV or T. gondii) that could be transmitted to island foxes.…”