A STUDY OF 'IMMEDIATE' SENSITIZATION BY ADSORPTION OF ANTIGENS AND ANTIBODIES IN VITRO
Annual interim progress rept. Sep 1967-Jul 1968
STANFORD UNIV CA DEPT OF PHYSIOLOGY
Pagination or Media Count:
The direct cardiotoxicity of streptolysin O SLO may be aggravated by an additional hypersensitivity reaction between SLO and specific, tissue- bound antibody. The isolated guinea pig heart responds to purified SLO with a rapid, transient decrease in rate and amplitude of contraction, superimposed on a gradual, irreversible loss of ventricular contractility. At ventricular standstill, the atria beat normally, as do electrically driven strips of the arrested ventricles. Ventricle strips from normal hearts are completely insensitive to the toxin. However, isolated atria respond to SLO with a reversible decrease in rate and amplitude of contraction accompanied by a marked, transient increase in the rate of repolarization of the intracellular potential. All of the transient changes are shown to be due to acetylcholine release by the atria the permanent ventricular decline results from a toxin- induced defect in atrioventricular conduction. Oxidized inactive SLO elicits the production of anaphylactic antibodies in the guinea pig, and when challenged with the oxidized or reduced active toxin, whole hearts and isolated atria from these animals respond anaphylactically and release histamine. Serum from rabbits immunized with the oxidized toxin passively sensitizes guinea pig cardiac tissue in vitro. These tissues, when challenged with either form of SLO, react anaphylactically and release histamine. The response of sensitized atria to reduced toxin consists of the depression of the direct toxic effect acetylcholine, followed by the potentiation of the anaphylactic reaction histamine. Thus, SLO can participate in multiple reactions with cardiac tissues.
- Medicine and Medical Research