Abstract

Introduction

Materials & Methods

Results

Discussion & Conclusion

References

Discussion
Board

The deposition C3 fragments, C3b, iC3b and C3dg, from HBM, identified by the antibody I3/15, were demonstrated on the killed serum susCeptible bacteria, Escherichia coli NCTC 8007, serotype 0111 K58(B4) H2.

Results showed that C-derived opsonins apparently have a greater affinity for MFGM than solid-phase killed bacteria. Diluting whole-milk in a detergent containing buffer led to an increased level of C3 fragments deposited on the killed bacteria. Whole-milk diluted in PBS buffer to deposit less C3b on the bacteria in comparison with whole-milk in 0.5% PBS-Tween-20 buffer. Tween-20 is a non-ionic detergent, capable of disrupting the MFGM through fat dissolution (Table 1). This probably led to the release of membrane-bound C fragments. The inhibition of optimal deposition of opsonin on killed bacteria by MFGM, was also observed using appropriate buffers supporting both the classical and alternative pathways of C activation, when whole-milk was compared to de-fatted milk samples. Deposition of opsonin was consistently greater in de-fatted milk compared to whole-milk samples. The inhibition of c activation was approximately equal for both the classical and alternative pathways in the colostrum, while the inhibition of the classical pathway predominated in the transitional milk (Table 2).

Table 1 Deposition of activated C3§ (opsonins) on killed E. coli 0111 bacteria by human breast-milk^a,c (results in µg/ml)

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                                       Colostrum    Transitional milk
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Post-partum duration of lactation      1-4 days        5-30 days
Heatedb whole-milk                     65 ± 10*        70 ± 5.5*
Whole-milk in PBS                      75 ± 28         87 ± 12.8
Whole-milk in PBS-Tw buffer           167 ± 34        110 ± 25
Whole-milk in dGVB2+ buffer             3 ± 2.2        -------
Partially de-fatted milk 
(x200-1500g) in GVB2+ buffer           84 ± 12         42 ± 6
Whole-milk in Mg-EGTAe buffer          -------         50 ± 6.8
Partially de-fatted milk 
(x200-1500g) in Mg-EGTA buffer         14 ± 5.6        64 ± 8.4
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Table 2. Degree of inhibition by milk fat for the utilisation of classical and alternate pathways of C activation by whole-milk samples to deposit activated C3 samples^{a, b}

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                                      Colostrum    Transitional milk
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Combined pathway: PBS vs PBS-Tw           55              21
Classical pathway (GVB 2+ buffer)         96              100
Alternative pathway (in Mg-EGTA buffer)   100             22
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a  results expressed in mean percentage 
b  calculated from results in table 1

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