Immunology & Immunological Disorders Poster Session
EFFECT OF EDTA AND HEAT-INACTIVATION OF COMP0LEMENT ON BACTERICIDAL ACTIVITY OF HUMAN BREAST-MILK
Figure 1. Effect of complement-inactivation and centrifugation (de-fattening process) on the
bactericidal activities of different human breast-milk samples against E coli 0111.
Figure 2. Comparison of the effects of heat-inactivation and and addition of EDTA on the
antibacterial activities of different human breast-ilkfractions.
C inactivation by heating at 56°C either abolished the bactericidal effect of the serum and milk samples or even enhanced their ability to support growth of bacteria after 2 hours of incubation. This probably supports the opinion that the complement system is the one of the most important component of normal breast-milk samples effecting bactericiolysis in the absence of inflammation.
CORRELATION OF BACTERICIDAL ACYTIVITY OF HUMAN BREAST-MILK WITH THE LACTATION DURATION
The level of bactericidal activity of the HBM corresponds closely to the reported levels of major C factors, initially rapidly declining from up to twice the serum levels in early colostrum, and more gradually in the transitional milk to stable low levels in mature milk (10).
DILUTION LIMIT OF BACTERICIDAL ACTIVITY
Table 1. Effect of dilution and heat complement inactivation on the bactericidal activity of normal human serum (results expressed in % bacteriolysis)
Degree of dilution 1:10 1:20 1:40 1:80 1:160 1:320 Normal human serum 100 100 100 62 60 38 Heateda NHS nil** nil*** nil nil nil nilNHS = Normal human serum
nil** = enhanced bacterial multiplication rather than bacteriolysis
a Heated at 56°C for 30 minutes
Correlation of bactericidal activity with opzonization of solid-phased killed bacteria
The maximal levels of C3 opsonins deposition from milk samples were obtained by dilution in detergent-containing buffer, compared to dilution in saline buffer, suggesting that the milk fat globule membrane (MFGM) strongly competes with the solid-phase bacteria for the deposition of opsonins. Fat clearance of the milk samples however failed to restore the deposition of opsonins to levels comparable to that of whole-milk in detergent buffer, suggesting that a significant portion of the native C components might also have been lost through centrifugation.
The opsonin deposition found in the milk that had been heated for 30 min at 56°C probably demonstrates the presence of pre-formed opsonins in-vivo.
* Real value of deposited opsonin with no substraction of the background opsonization.
b Values obtained after substraction of the background level of opsonization(opsonization by heated wholemilk)
c Results expressed in µg/ml (Average ± SEM)
d Wholemilk heated to 56°C for 30 minutes
Table 3. Relative contribution of different antibacterial components of human breast-milk to the observed lysis of E coli bacteria a b
Antimicrobial component Colostrum Transitional milk Mature milk Complement 83 13 15 Lysozyme 0 8 0 Free fatty acid 13 0 0 Total bactericidal capacity 95 19 15a Estimated from various results data b Results expressed as units of % Bacteriolysis
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|Ogundele, M.O.; (1998). Bactericidal Activity of Human Milk Complement System. Presented at INABIS '98 - 5th Internet World Congress on Biomedical Sciences at McMaster University, Canada, Dec 7-16th. Available at URL http://www.mcmaster.ca/inabis98/immunology/ogundele0172/index.html|
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