FISHERY BULLETIN: VOL. 69. NO, 3 



DISCUSSION 



In the development of information and prin- 

 ciples of invertebrate internal defenses, con- 

 sistent and entirely natural attempts have been 

 made to translate findings into the concepts and 

 compartments constructed for the immune re- 

 sponses of vertebrates. The effort has led to 

 some confusion of terminology and even to lack 

 of agreement about definitions of immunity. 



The concept of immunity in vertebrates has 

 been admirably stated by Good and Papermaster 

 (1964), who define immunity precisely and nar- 

 rowly as "a biologic phenomenon embodying pri- 

 mary and secondary responses, with antibody 

 synthesis and release, reactions of immediate and 

 delayed allergy, and homograft immunity." 

 They state: "To the time of writing [1964], 

 adaptive immunologic responsiveness has not 

 been demonstrated in the invertebrates." They 

 then define adaptive immune responsiveness as 

 "the ability to respond to antigenic material by 

 production of specific combining substances, and 

 to show an anamnestic response to these same 

 antigens on subsequent exposure." Their con- 

 tinued exposition of immunity from the verte- 

 brate point of view includes the following signifi- 

 cant points: 



1. "Adaptive immunity ... is primarily a func- 

 tion achieving full expression late in phylogeny 

 and ontogeny." 



2. "The l>-mphoid cell family is the primary 

 cellular basis for adaptive immune response in 

 vertebrates . . . ." 



3. "The possibility that another cell system 

 may mimic adajitive immune resi)onses in an in- 

 vertebrate species cannot be excluded at this 

 time." 



A broader, more inclusive, concept of immu- 

 nity has been suggested recently. If the broader 

 definitions of terms projiosed by several authors 

 are accepted, the words "immunity" and "im- 

 mune response," rather than careful circum- 

 locutions, can be used with invertebrates. As 

 an example, McKay and Jenkin (1969) stated 

 that the Australian freshwater crayfish was ca- 

 jialjle of an "adaiitive immune resjionse." Such 

 a capability is not possible within the confines 



of Good and Papermaster's definition of adaptive 

 immunity as the production of specific immuno- 

 globulins (a capacity which has been correlated 

 with the occurrence of lymphoid tissue) . Per- 

 haps their definition is too restrictive and rigid, 

 since a number of invertebrates do show re- 

 sponses that protect them from pathogens (hence 

 they are adaptive) . 



Earlier definitions of antibodies and immunity 

 allowed more latitude for inclusion of inverte- 

 brate responses. Cantacuzene (1923b) , for ex- 

 ample, considered as antibodies ". . . toute sub- 

 stance albuminoide du plasma, douee ou non de 

 sjiecificite, qui, se fix.mt sur I'antigene, modifie 

 les relations de contact de ce dernier, soit avec 

 les cellules, soit avec les autres constituants 

 chimiques des humeurs." 



McKay, Jenkins, and Rowley (1969) stated 

 ". . . to allow comjiarisons to be made between in- 

 vertebrate phyla and the vertebrates . . . the defi- 

 nitions of the immune response should be as 

 broad as possible and emphasis placed on the 

 functional aspects . . . ." These authors suggest 

 that such a definition of the immune response 

 might be "the ability of the animal to respond 

 to a foreign particle (whether it be truly foreign 

 or unwanted self) by the iiroduction of s]5ecific 

 proteins capable of reacting with the inducer, 

 and the resultant of this reaction leading to 

 phagocytosis." 



Gushing (1967), in an excellent summariza- 

 tion of invertebrate immune mechanisms, stated 

 "There is a growing consensus of observations 

 supporting the view that while vertebrates and 

 invertebrates may share some basic immune 

 competences such as 'innate immunities' and 

 phagocytic cells, it is indeed only within the 

 vertebrates that the full capacity of adaptive im- 

 munity exists." This statement seems reason- 

 able, and fits the confines of Good and Paper- 

 master's narrow definition of adajitive immunity, 

 but is too negative if a broader perspective of 

 immunit.v — such as that proposed by McKay, 

 Jenkins, and Rowley — is adojjted. 



Probably greater emphasis should be jilaced 

 on the cidaptive aspects of invertebrate internal 

 defense processes. Substantial numbers of 

 studies have indicated the existence of adaptive 

 responses to experimental inoculations of for- 



476 



