Immune response to moxalactam in rabbits and in humans

Three of 23 New Zealand white rabbits immunized with moxalactam or bovine serum albumin (BSA)-moxalactam conjugates produced specific antimoxalactam antibodies. Rabbits that produced antimoxalactam had been immunized, by a novel approach, with heat-aggregated BSA-moxalactam conjugates containing Corynebacterium parvum as adjuvant. Use of liposomes to augment antibody response in the rabbits was successful for the production of anti-BSA antibodies, but failed to result in production of antimoxalactam. One antimoxalactam was chosen for further study, was specifically inhibited with moxalactam (10(-5) mol/L), and did not cross-react with any of the 11 other cephalosporins or eight penicillins tested (in concentrations of 10(-2) mol/L). In addition, the antibody did not demonstrate any carrier specificity. One of eight humans receiving intravenous moxalactam therapy developed a low titer, low avidity antimoxalactam. This patient was a "good responder," inasmuch as he also produced three transfusion-stimulated alloantibodies to red cell antigens during the study. Although the patient developed the antimoxalactam antibody while the drug was being administered, there was no evident adverse clinical reaction. This is the first report of antimoxalactam produced either in experimental animals or in humans. Our data indicate that moxalactam may be a relatively poor immunogen in rabbits requiring special immunization protocols. The one antibody studied does not cross-react with other structurally related antibiotics. Although human antimoxalactam may be produced, no adverse effects were detected in the one case observed.