Neuraminidase promotes neutrophil, lymphocyte and macrophage infiltration in the normal rat kidney

Neuraminidase (NA) is an enzyme produced by several microorganisms, which is capable of liberating sialic acid from glycoproteins and modifying cellular adhesion mechanisms. NA is considered a virulence factor in some bacterial species and has been implicated in the pathogenesis of acute poststreptococcal glomerulonephritis, a disease in which glomerular leukocyte infiltration is a prominent feature. We examined the effect of NA on kidney infiltration by neutrophils (PMN), T lymphocytes (TL) and monocyte-macrophages (MM). Intravenous injection of NA resulted in an early increase in the number of PMN (1 hr, 3.42 +/- 0.19 cells/cgs, mean +/- SEM; 3 hr, 3.63 +/- 0.13; 6 hr, 2.9 +/- 0.24; controls, 1.53 +/- 0.18; P < 0.001) and MM (1 hr, 3.49 +/- 0.16; 3 hr, 4.02 +/- 0.2; 6 hr, 3.88 +/- 0.27; controls 1.43 +/- 0.14; P < 0.001) in the glomeruli, while TL increased later (24 hr, 2.29 +/- 0.14; 48 hr, 2.4 +/- 0.2; 72 hr, 2.16 +/- 0.15; controls 0.7 +/- 0.07; P < 0.001). PMN and TL were also increased in the interstitium (up to ninefold for PMN and up to threefold for TL). Following i.v. injection of 51Cr-labeled NA-treated leukocytes, renal radioactive uptake was significantly increased at all times tested (percent radioactivity/gram of tissue after PMN injection, 3 hr, 5.57 +/- 0.46, mean +/- SEM; 12 hr, 5.38 +/- 0.77; 60 hr, 6.51 +/- 1.1; controls, 1.26 +/- 0.17, 1.75 +/- 0.25, and 2.46 +/- 0.08, respectively; P < 0.001 in each case.(ABSTRACT TRUNCATED AT 250 WORDS)