Combined Active—Passive Re-Immunization against Tetanus in Previously Immunized Individuals: Experimental and Clinical Evidence

Abstract

Combined active-passive re-immunization against tetanus was studied in 29 previously actively immunized rabbits by means of tetanus antitoxin titrations. Both fluid and alum-precipitated tetanus toxoids in doses of 0.05 or 0.1 ml were used. Commerical tetanus antitoxin was employed in a dose of 150 units (except as in (c) below). When these doses of antitoxin and toxoid were injected into opposite extremities, the initial increase in titer due to the injected antitoxin was followed in 3 to 6 days by a higher and prolonged secondary increase. This latter could only be a true secondary immune response. When toxoid and antitoxin were mixed in the same syringe no response occurred. Increasing the dose of separately injected antitoxin 3.3 fold led to higher initial titers but did not suppress the secondary immune response. The addition of hyaluronidase to the toxoid did not speed the secondary immune response but appeared to increase the total amount of homologous antitoxin produced by the animals. Four previously immunized individuals, two children and two adults, were studied following accidental wounding. They were injected with the usual prophylactic dose (1500 units) of tetanus antitoxin and, in the opposite extremity, either fluid or alum-precipitated tetanus toxoid. Following initial increases in titer due to the antitoxin, three of the four exhibited secondary immune responses to the toxoid 4 to 5 days later.