STUDIES ON THE MECHANISM OF RECOVERY IN PNEUMOCOCCAL PNEUMONIA : II. THE EFFECT OF XXXX THERAPY UPON THE PULMONARY LESION OF EXPERIMENTAL PNEUMONIA.

@entity11682 @entity55 @entity75 @entity4 @entity19453 @entity35 @entity2258 @entity2259
@entity2258 was produced in albino @entity35 by intrabronchial inoculation of Type I pneumococci suspended in @entity19453 . The resulting @entity55 was uniformly fatal in untreated @entity35 . Eighty per cent of the animals so infected and treated with @entity11682 drugs 6 hours after inoculation survived the @entity55 . At the end of 1 week the surviving animals were sacrificed, and examination of the lungs showed sharply demarcated localized pulmonary lesions containing no pneumococci. Microscopic study of the lungs of treated animals sacrificed at 6, 18, 42, 66, 96, and 168 hours after the start of treatment revealed the following sequence of events. During the first 18 hours the drug apparently had little effect upon the @entity75 , but at the end of 18 hours pneumococci in the @entity4 zone began to show striking changes in their morphology, indicating bacteriostesis. Forty-two hours after the start of treatment the @entity4 zone had disappeared, the @entity55 had ceased to spread, and the pneumococci at the margin of the lesion had been overtaken by leucocytes. Careful examination of the exudate in the periphery of the lesion revealed definite phagocytosis of pneumococci. By the 4th day no pneumococci could be found in the stained sections, and after 1 week there remained only macrophages in the rapidly clearing alveoli. In order to demonstrate the phagocytic reaction more clearly the effect of @entity11682 drugs was studied in pneumonic @entity35 previously rendered leucopenic by exposure to x-ray. The @entity55 in these animals was relatively acellular, and the few macrophages present in each alveolus could be seen to have phagocyted large numbers of pneumococci after 18 to 42 hours of treatment. The macrophages not only phagocyted the pneumococci but ultimately destroyed them, the @entity75 later going on to complete resolution. The fact that this phagocytic reaction was observed in the lungs of animals with @entity2259 suggests that the phagocytosis is independent of circulating type-specific opsonins.
