Defective natural killer cell cytotoxic activity in feline immunodeficiency virus-infected cats.

Flow cytometry has been employed to study NK cell cytotoxic activity in cats infected with feline immunodeficiency virus. The results show that animals infected for 12 months or more have decreased levels of NK cell cytotoxic activity in their blood. The impairment could not be overcome by in vitro treatment of effector cells with interleukin 2. Additional results suggest that the NK cells of infected cats are defective, in that they are still able to bind to target cells but have a reduced ability to kill them.

C-reactive protein in acute otitis media.

This study was designed to explore whether C-reactive protein (CRP) in serum is helpful in assessing the etiologic diagnosis of acute otitis media (AOM) in children. CRP was measured serially by a radial immunodiffusion method in sera from 67 children with AOM and in 67 matched controls, affected by noninfectious neurologic disorders. In the study group 43 (64%) children had a confirmed bacterial AOM and 24 (36%) showed no bacterial growth from middle ear fluid. The upper limit of CRP in controls was 15 mg/liter. Concentrations of CRP in patients with bacterial AOM ranged from less than 6 to 150 mg/liter; in 71% of the cases the value was greater than 15 mg/liter. In the patients with sterile middle ear fluid CRP ranged from less than 6 to 110 mg/liter; in 67% of the cases the level was greater than 15 mg/liter. CRP greater than 15 mg/liter showed sensitivity of 72%, specificity of 33%, predictive value of a positive test of 66% and predictive value of a negative test of 40%, in detecting bacterial AOM. Measurement of CRP should not be used in the decision regarding antimicrobial therapy for AOM in children.

Amoxicillin twice daily in the treatment of acute otitis media in infants and children.

A total of 110 children with acute otitis media were assigned randomly to treatment with 60 mg/kg per day amoxicillin in a twice-daily (group A) or a thrice-daily (group B) regimen for 10 days. Patients were scheduled for follow-up examinations at mid-treatment, 5 days after the end of therapy and 30, 60, 90 days after starting therapy. At 15 days 6 out of 55 patients (10.9%) treated with amoxicillin twice daily were considered treatment failures compared to 4 children (7.2%) in the thrice daily group. Rates of cure, recurrent otitis media and persistent middle ear effusion were comparable in the two groups of patients at later time intervals. By 90 days the total cure rate was 42.3% (22/52) in children treated twice daily and 41.5% (22/53) in those who had received amoxicillin thrice daily. At the same time persistence of bilateral and unilateral effusion was noted in 12/52 (23.1%) and 8/52 (15.3%) children in group A and in 16/53 (30.1%) and in 10/53 (18.9%) in group B respectively. No significant difference was noted in the two treatment regimens with regard to adverse side effects. Because reduction in division of the amoxicillin dose caused no significant difference in the efficacy of antibiotic treatment of acute otitis media in infants and children, we think that this simplified scheme of therapy can routinely be used in clinical practice and thus improve compliance to antibiotic administration.

Circulating immune complexes and analysis of renal immune deposits in feline immunodeficiency virus-infected cats.

Total immunoglobulin content and concentration of immune complexes (IC) were determined in the sera of 51 cats infected with feline immunodeficiency virus (FIV) and of 40 controls. IgG and IgM were quantified by radial immunodiffusion and circulating IC (CIC) by the CIC-conglutinin assay. IgG fractions were obtained by acid elution from kidney tissues of 15 FIV-infected and five negative control cats to investigate the possible role of IC in the genesis of renal damage observed in infected animals. Mean concentrations of IgG and circulating IC were higher in FIV-infected cats than in controls (29.6 +/- 6.7 versus 23.0 +/- 1.9 mg/dl (mean +/- s.d.) P < 0.001; and 66.5 +/- 17.0 versus 27.4 +/- 19.9% I, P < 0.001, respectively), while IgM levels were only slightly increased (0.9 +/- 0.05 versus 0.87 +/- 0.04 mg/dl, P < 0.02). Immunoglobulin fractions were eluted from 10 of the 15 renal tissue samples from FIV-infected cats and were found to be polyclonal and at least partly specific for FIV antigens. These findings confirm the presence of a B cell activation in FIV-infected cats and demonstrate the presence of high levels of CIC in their sera. The presence of immune deposits in renal tissues suggests that IC might play a role in the pathogenesis of the renal damage observed in FIV-infected cats.