Expression of major histocompatibility complex class II antigens in porcine leptospiral nephritis.

Class II major histocompatibility complex (MHCII) is required for the presentation of antigens to CD4 helper T cells. During nephritis, not only primary antigen presenting cells such as histiocytes and lymphocytes, but also cytokine-stimulated tubular epithelial cells express MHCII. Leptospirosis in fattening pigs is characterized by several degrees of nephritis, from absence of lesions to severe multifocal tubulo-interstitial inflammation. Renal tissue from 20 8-month-old pigs with spontaneous nephritis and 6 control pigs without renal lesions were investigated for leptospirosis by indirect immunohistochemistry (IHC) and polymerase chain reaction (PCR). IHC for MHCII also was performed on renal samples. Serum samples were tested for different serovars of Leptospira interrogans. Control pigs were free of interstitial nephritis and negative for leptospirosis by all tests. In pigs with nephritis, serology was positive for serovar Pomona in 19/20 pigs. In 16 of these 19 pigs, leptospiral renal infection was confirmed by PCR and/or indirect IHC. Nephritic lesions were classified histologically into perivascular lymphocytic (4 pigs), lymphofollicular (6 pigs), lymphohistiocytic (8 pigs), and neutrophilic (2 pigs) pattern. MHCII expression by histiocytes and lymphocytes was observed in all lesions. Prominent MHCII expression in regenerating tubular epithelium was observed in lymphofollicular and lymphohistiocytic nephritis. No tubular colocalization between leptospiral and MHCII antigen was observed. Results suggest that during leptospiral nephritis, MHCII contributes to the intensity of the inflammatory response. Furthermore de novo MHCII expression in regenerating tubules may play a role in the defence mechanism against leptospiral tubular colonization.

[Blood filtration for the prevention of microaggregate damage: various critical aspects]. / La filtrazione del sangue nella prevenzione dei danni da microaggregati: alcuni aspetti critici.

Recent studies shown that patients receiving more than 20% of their total blood volume through 170 mu standard blood filters, may occur in severe organic damage such as pulmonary, cerebral, renal embolism due to microaggregates contained in stored blood. Microaggregate size varies from 10-200 mu; they are composed of platelets, leucocytes, red cells debris and fibrin strands, which take form few hours after blood storage begins and whose number progressively increases. In this study we analyzed microaggregate composition, factors causing their formation, side effects due to massive transfusion and blood filtration techniques capable to prevent a direct blood infusion. There is a variety of available filters, but screen filters seem to offer more important and practical advantages than depth filters do. The use fine pore filters is recommended when more than three blood units are to be infused during only one administration.