PROTECTION AGAINST NONTYPABLE HAEMOPHILUS-INFLUENZAE FOLLOWING SENSITIZATION OF GUT-ASSOCIATED LYMPHOID-TISSUE - ROLE OF SPECIFIC ANTIBODY AND PHAGOCYTES
Fj. Wallace et al., PROTECTION AGAINST NONTYPABLE HAEMOPHILUS-INFLUENZAE FOLLOWING SENSITIZATION OF GUT-ASSOCIATED LYMPHOID-TISSUE - ROLE OF SPECIFIC ANTIBODY AND PHAGOCYTES, Immunology and cell biology, 73(3), 1995, pp. 258-265
Rats intestinally immunized with whole killed non-typable Haemophilus
influenzae clear this organism from the lungs faster than non-immunize
d rats. This study investigated the role of antibody and phagocytes in
the clearance mechanism. First, dose-response experiments demonstrate
d that while lowering the dose of non-typable H. influenzae reduced th
e level of detectable specific antibody in bronchial washings, the abi
lity to accelerate bacterial clearance persisted to much lower doses.
Second, specificity experiments showed that intestinal immunization wi
th non-typable H. influenzae cross-protected against Pseudomonas aerug
inosa, even though antibodies were not absorbed out of serum by incuba
tion with P. aeruginosa. Third, serum antibody was shown to be bacteri
cidal for non-typable H. influenzae in the presence of complement (P <
0.05), while bronchial washings antibody was not. The bactericidal ef
fect of the serum was abrogated by the addition of bronchial washings.
Fourth, an ELISA quenching assay demonstrated that neutrophils from i
ntestinally immunized rats were able to phagocytose mote bacteria in a
given time period (P < 0.05) than unimmunized rats and rats immunized
by other routes. In the fifth experiment, the chemotactic response of
neutrophils to casein was shown to be significantly depressed by the
addition of bronchial washings obtained from immunized rats (P < 0.01)
. It is proposed that specific antibody in bronchial washings does not
have a direct role in opsonizing bacteria for killing or phagocytosis
, but instead has an anti-inflammatory effect. Non-specific effecters
such as neutrophils driven by specific immune cells are a likely means
of clearance of bacteria following intestinal immunization and acute
challenge.