THE STUDY OF URINARY SECRETORY IgA

(III). In Vitro Study of Its Antibacterial Activity

Abstract

To understand the significance of urinary Secretory IgA (SIgA) in the urinary local immunity, we developed an Enzyme-linked immunosorbent Assay (E. L. I. S. A.) method for better detection. Previously, we reported on the urinary immunoglobulins level in normal controls, the localization of urinary SIgA at the urinary tract and the SIgA values in various urological disease. In this paper, we studied the antibacterial activity of SIgA in vitro.
The summary of the conclusion obtained is as follows;
1) Purified SIgA originated from human colostrum alone did not reveal the antibacterial activity against E. coli NIHJ JC-2 at a concentration of 6.3μg/ml to 100μg/ml in Trypticase Soy Broth (TCSB). Egg-white Lysozyme alone was not an effective either in inhibiting the growth of this strain, but urea had an inhibitory action on bacterial growth in proportion to its concentration. In the condition adding 2μg/ml of Lysozyme and 3% of urea in TCSB, 1μg/ml of SIgA from colostrum revealed a bacteriostatic activity for about 4 hours.
2) Normal human urines were proved to have a slight bacteriostatic activity against E. coli, but this activity did not show good correlation to the urinary SIgA level detected with E. L. I. S. A.. Urine from patients recently-infected by E. coli had a marked bacteriostatic action against E. coli NIHJ JC-2. Of such urines, one was bacteriocidal against not only E. coli but also S. aureus FDA 209P, P. aeruginosa Shogen and K. pneumoniae PCI 602. In this urine, after absorption of SIgA with anti SC, P. aeruginosa only began to grow again. Therefore, it was suggested that urinary SIgA took part in this antibacterial activity.