THE RELATION OF CIRCULATING ANTIPNEUMOCOCCAL IMMUNE SUBSTANCES TO THE COURSE OF LOBAR PNEUMONIA I. NATURAL IMMUNE SUBSTANCES

Abstract

I. In 29 cases of pneumococcus lobar pneumonia (PLP) no relation was found between the presence or absence of detectable humoral immunity (detd. by testing the pneumococcocidal-promoting action of the serum), and the extension of the lesion. Active spread of the process from lobe to lobe occurred in certain patients, showing the persistence of a normal pneumococcocidal power in the blood. In other cases in which the serum lacked this property the lesion showed no increase in size throughout the period of observation. Likewise the initial conc. of immune substances in the blood had no observable significance in relation to the outcome of the disease. Patients without detectable humoral immunity were just as likely to recover as those showing this property to a normal degree. Bacteria, however, were absent from the blood of all but one of the patients in whom the serum showed a normal pneumococcocidal-promoting power, and frequently but not invariably present in patients whose sera originally lacked or later had lost this power. Hence the authors conclude that the natural circulating antipneumococcal immune substances play at most a very minor role in the course of PLP.[long dash]II. . Acquired antipneumococcal immune properties were detected in the serum of all of 24 PLP cases recovering, and in only 1 of 6 fatal cases; but the onset of immune reaction did not coincide with the onset of recovery, often occurring 2-3 days before or a day or so afterward. Serial x-rays showed that the extent of the lesion increased after the appearance of immune bodies in 6 cases but not in most. Bacteremia ceased either when demonstrable humoral immunity appeared or before. However, the blood remained sterile throughout the course of the disease in several cases, showing neither natural nor acquired immunity. Furthermore, the pulmonary lesion remained static for a no. of days in some cases showing a similar lack of antipneumococcal activity in their blood serum. These findings suggest that either the body brings into play more than one mechanism for restraining the spread of the pneumococcic process, localizing the invading microorganism within the lesion and eventually terminating the infection, or the elaboration of humoral immune substances represents only one phase of a specific reaction against the pneumococcus.[long dash]III. Observations on the authors'' 29 cases of PLP, and those of others, suggest that in the early phases of the disease, before consolidation has developed to its max. intensity, the specific antibodies are capable of so affecting the pneumococci in the lesion as to bring about a rapid cessation of the disease process; but after this stage has been reached the chief effect of the antibodies is to confine the pneumococci to the pulmonary lesion and to prevent extension of the pathologic process, the actual termination of the disease being occasioned by the unknown process of natural recovery.