Humoral and cellular immunity in spontaneous feline infectious peritonitis

HUMORAL AND CELLULAR IMMUNITY IN SPONTANEOUS FELINE INFECTIOUS PERITONITIS Paltrinieri S.*, Cammarata Parodi M.**, Cammarata G.**, Comazzi S.* * Istituto di Patologia Generale Veterinaria - Milano - Italy; ** Istituto di Anatomia Patologica Veterinaria e Patologia Aviare - Milano - Italy Vascular lesions in Feline Infectious Peritonitis (FIP) are thought to be caused by a type III hypersenstivty reaction, while histology of the granulomas suggest a type IV hypersensitivity. To further investigate the pathogenesis of the disease we analized some aspects of humoral and cellular immunity in FIP. Haematology, antibody titers and protein electrophoresis in serum and in effusions from 48 FIP affected cats were studied. The results were compared with those of 20 healthy cats. The distribution of the immune cell and of the virus in FIP lesions were also studied by immunohistochemistry using antibodes against myelomonocytic (MAC387), and lymphoid (CD3, CD4 and CD8 for T-cells and IgM and IgG for B-cells) antigens. Seropositive animals (antibody titer>1:100) were present either among the FIP infected cats (73%) either among the healthy cats (72%). FIP infected cats had neutrophilic leukocytosis (P>0.05), lymphopenia (P<0.05) and hyperglobulinemia (P<0.01) with increased \uf0612 (P<0.05) and \uf067 globulins (P