Antibodies to Meningococcal H.8 (Lip) Antigen Fail to Show Bactericidal Activity
WALTER REED ARMY INST OF RESEARCH WASHINGTON DC DIV OF COMMUNICABLE DISEASE AND IMMUNOLOGY
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Purified H.8 Lip antigen was coupled to tresyl-activated Sepharose 4B and used in affinity columns to purify anti-Lip antibodies from convalescent patient sera and from immune rabbit sera. Affinity-purified anti-Lip antibodies isolated from two convalescent patient sera contained 1000 and 1280 ELISA units of antibody and included antibodies of IgG, IgA, and IgM isotypes. An anti-Lip mouse monoclonal ascites 2-1-CA2 had 2 400 ELISA units of antibody. Bactericidal assays were performed using three different case strains of Neisseria meningitidis group B, namely 4476, 8532, and 8047. Neither preparation of purified human anti-Lip antibodies had detectable bactericidal activity against strains 4476 and 8532, but one of the two had a titer of 14 against strain 8047. Anti-Lip antibodies that were purified from immune rabbit serum and contained 1600 ELISA units of anti-Lip antibodies also failed to show detectable bacterial activity. The rabbits were immunized with purified Lip antigen and showed specific antibody levels of 2000-2200 units by ELISA, but even the unfractionated sera had little or no bacterial activity against the test strains. The high titer mouse monoclonal ascites had no bacterial activity against the test strains. The poor bactericidal activity associated with monoclonal and polyclonal antibodies to the Lip antigen suggest that in spite of other attractive properties it may not be useful as a meningococcal vaccine. Keywords Anti lip antibodies Bactericides Reprints.