Studies on the Experimental Cardiac Involvement and Cell-Mediated Immunity in Germ-Free Mice Sensitized with Killed Group A Streptococci

Abstract

Electrocardiographic changes and cell-mediated immunity in germ-free mice sensitized with formalin-killed group A streptococci were studied. In germ-free mice sensitized with formalin-killed group A streptococci, a marked prolongation of the PQ interval in electrocardiogram (ECG) was observed at the fourth and seventh week of the sensitization, and significant increases of [³H] thymidine uptake of lymphoid cells by stimulation with phytohaemagglutinin (PHA-M), pokeweed mitogen (PWM) and streptococcal mucopeptide were ob-served at the second, third and sixth week of the sensitization. Moreover, in macrophage migration inhibition test, migration inhibition of macrophages by streptococcal mucopeptide antigen was seen at the third, fifth and sixth week, and by heat-killed streptococci at the first and third week of the sensitization. In contrast, no electrocardiographic change and slight increases of [³H] thymidine uptake of lymphoid cells by stimulation with mitogens or streptococcal antigens were observed in non-sensitized germ-free mice and also in germ-free mice sensitized with formalin-killed staphylococci or treated with physiological saline.
In germ-free mice sensitized with streptococci, their body weight did not increase and cyanosis on lips or extremities of the mice was noted throughout the experimental period.
Light microscopic histological examination could not reveal any changes that suggest damage of the myocardial tissue.