CHAPTER LXX 

 ANTIBACTERIAL SERA 



F. M. HUNTOON and R. H. HUTCfflSON 

 H. K. Mulford Co., Philadelphia, Pa. 



Antibacterial sera are those containing immune bodies whose action is directed 

 against bacteria as entities or against the products of their disintegration, or possibly 

 against some product of their metabolism. This action is in contradistinction to the 

 action of antitoxins, in which the antibody acts by neutralizing a toxic principle 

 elaborated by the organism, either as a product of metabolism or as a result of ferment 

 action on some of the substances present in its environment. 



The antibacterial immune bodies also apparently differ from the antitoxins in 

 their physico-chemical make-up, since they are found in a different fraction of the 

 serum — one that is precipitated by a comparatively low concentration of ammonium 

 sulphate. 



The immune bodies classified as "antibacterial" differ among themselves in their 

 mode of action. Agglutinins and precipitins, which are probably identical, act di- 

 rectly on their antigen without the aid of a third factor. Opsonins or tropins, the 

 so-called "protective" antibody, the complement fixation antibody, and the bac- 

 teriotrophic or bacteriolytic antibodies perform their specific function only in con- 

 junction with complement. Since agglutinins and precipitins are believed to have 

 little to do with the curative action of such sera, it follows that the therapeutic value 

 of antibacterial sera depends on those antibodies which require complement, and 

 also, in the case of the tropins, on the ability of the patient's phagocytes to function. 

 In the treatment of disease with antibacterial sera, the time factor is, therefore, a very 

 important consideration since a failure on the part of the patient to supply active 

 complement or active leukocytes involves the failure of the immune bodies to perform 

 their specific function. Many disappointments of specific therapy may be attributed 

 to this cause. 



Antibacterial sera as a whole have not had the wide use, nor have the results ob- 

 tained been comparable to those obtained with diphtheria antitoxin. There are 

 various reasons for this, including failure to use such sera early in the disease, the 

 tendency being to employ such measures only as a last resort. 



Emphasis on the importance of early treatment with antibacterial sera is justified 

 by the results that have been obtained in the use of an ti-meningococcic serum. This is 

 well illustrated in Table I, compiled by Blackfan' from the published reports of 

 various observers. 



Another, and probably the most important, reason for the lesser efficiency of anti- 

 bacterial sera is the extreme specificity which is an inherent quality of such sera. 

 For instance, monovalent sera against any fixed type of the pneumococcus have no 



' Blackfan, K. D.: Medicine, i, 139. 1922. 



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