STUDIES ON THE PHAGOCYTIC FUNCTION OF URINARY LEUKOCYTES

Abstract

The phagocytic function of urinary leukocytes of patients with urinary tract infection (UTI) was studied.
Urinary leukocytes were alive irrespective of the type of UTI, urine osmolarity or pH. The mean rate of the viability was observed to be 82%. The rate of phagocytosis, the percentage of leukocyte phagocytizing bacteria in all urinary leukocytes, was high under the urine condition of low osmolarity (≤600mOsm/L) and nearly neutral pH. The mean rates of phagocytosis of patients with acute cystitis, acute pyelonephritis, chronic cystitis, and chronic pyelonephritis were 3.0%, 2.1%, 13.2%, and 18.3%, respectively. The rate of phagocytosis of acute UTI was kept very low regardless of urine bacterial count; however, in chronic UTI, this rate increased in accordance with urine bacterial count.
The rate of phagocytosis of patients with indwelling catheters was higher than that of patients without catheters.
All chronic cystitis patients with indwelling catheters and 58% of chronic cystitis patients without catheters showed to have positive tests for antibody-coated bacteria (ACB). The opsonic effect of ACB could not be confirmed.
The phagocytic function of urinary leukocytes was also studied in vitro. By the Lab-Tek chamber method, the rate of phagocytosis was 20 to 30% in normal and infected urine regardless of urine osmolarity. By the tube method, the phagocytosis was almost none in urine with osmotic pressure higher than 600mOsm/L, and even in urine with osmotic pressure lower than 600mOsm/L the rate of phagocytosis was lower than 5% in many cases.
However, the rate of phagocytosis apparently increased in urine with osmotic pressure lower than 600mOsm/L by centrifuging the tubes, which means acceralated contact of leukocytes and yeasts. No difference in the rate of phagocytosis was observed between normal urine and infected urine.
The following three experiments were counducted by the transmission electron microscope; morphological study of urinary leukocytes of patients with various types of UTI, observation of phagocytosis in infected urine added with latex particles, and that of phagocytosis in aseptic pyuria added with bacteria.
The above results suggest that leukocytes in urine are not mere passive spillover as long considered but taking a part of defense function against ascending UTI.