Host-pathogen interactions in experimental Mycoplasma pneumoniae disease studied by the freeze-fracture technique.

The application of freeze-fracture and organ culture technology to the study of disease caused by Mycoplasma pneumoniae provided a new perspective on host-pathogen interactions. Structural variations of the M. pneumoniae membrane and alterations of the host cell membrane that are induced by this pathogen during experimental infection were observed. Study of freeze-fracture preparations of M. pneumoniae revealed the presence of numerous membrane-associated particles embedded in the inner aspect of the bimolecular leaflet. However, areas of the fractured membrane of cells sometimes had particle-free zones and/or blebs. These particle-free areas were sometimes closely aligned to host tracheal epithelium in organ culture. In addition, marked changes in the membrane integrity of the host epithelium during experimental infection were observed. Deterioration of luminal surface membranes and alterations in the distribution of ciliary intramembranous particles were frequently noted. Ciliary dysfunction was also suggested by observations of abnormally aligned and clumped adjacent cilia. These findings correlated well with biochemical data demonstrating altered host macromolecular synthesis and observations of ciliostasis during experimental M. pneumoniae infection.