Evaluation of Pgp (MDR1) immunohistochemistry in canine lymphoma - prognostic and clinical aspects.

Permeability glycoprotein (P-glycoprotein, Pgp) immunohistochemistry (IHC) was evaluated in dogs with multicentric lymphoma treated with cyclophosphamide- doxorubicin-vincristine-prednisolone with or without L-Asparaginase. Lymph nodes of 33 untreated dogs were immunophenotyped: Ki67% and Pgp analyses (with anti-Pgp, monoclonal mouse C494 clone) were performed. Pgp positivity rate and intensity were determined microscopically (by manual counting done by two blinded authors in two parallel specimens). The median overall survival time (OST) was 333 days and the relapse-free period (RFP) 134 days. Pgp expressions were positive in 18 out of 33 (54.5%) of tumour cells. T-cell types stained more intensively. Lower OST and RFP were found with Pgp positivity ≥ 35% (OST: 240 days, RFP: 95 days) compared to Pgp positivity < 35% (OST: 428 days, RFP: 232 days). Intensive staining was associated with a lower OST and RFP (240 and 103 days, respectively) than weak staining (428 and 221 days, respectively). Death due to adverse drug reactions was best predicted at Pgp positivity ≤ 6.5% (sensitivity/specificity: 0.55/0.81) and ≤ 123 days (sensitivity/ specificity: 0.55/0.86). Pgp evaluation by IHC can have prognostic value with a properly established Pgp% positivity cut-off value in dogs treated with Pgp substrate drugs.

Cystatin C analysis in the dog: a comparison of turbidimetric and nephelometric assay results.

Cystatin C is a serum protein with low molecular mass, which has been suggested as a marker to assess renal function in the dog. This protein is regularly assessed using particle-enhanced turbidimetric immunoassay (PETIA) and particle-enhanced nephelometric immunoassay (PENIA), in which rabbit anti-human cystatin C antibodies are used. The purpose of this work was to compare the results of cystatin C analysis obtained by PETIA and PENIA assays in the dog. Forty dogs of different genders and breeds were classified into four groups of 10 animals each based on serum creatinine concentrations (4 stages of chronic kidney disease). Serum cystatin C concentration was measured using PETIA and PENIA assays, the results were compared, and correlation with serum urea and creatinine concentrations was established. The correlation coefficient for results obtained using PETIA and PENIA assays was r = 0.706. Serum cystatin C concentrations obtained in PETIA had a lower correlation coefficient with creatinine concentrations than those found in PENIA (r = 0.614 and r = 0.904, respectively); similarly, serum cystatin C was less correlated with serum urea concentration in PETIA than in PENIA (r = 0.463 and r = 0.636, respectively). The results obtained in this study suggest that the nephelometric assay is more sensitive and was shown to be more closely correlated with other renal function indicators than the PETIA assay.