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Demonstration of the “spreading factor” in the cercariae of Schistosoma mansoni
Demonstration of the “Spreading Cercariae of Schis tosoma Robert Depurt,tLeut
oj Helvlintholog2/,
E.
Factor” manson
in the
Iiuntz?J
U. S. Xaual Jledical Research Unit No. 3, American Edassy, Cairo, Egypt
(Submitted for publication,
9 October 1952)
General terms such as histolytic:, proteolytic and mucolytic enzymes, digestive juices and ferments, and penetration secretions, have been used loosely in referring to the chemical aids which augment the mechanical entry of tissue-penetrating parasites into t’heir hosts. These terms a;pear frequently in studies relating to the cercariae of trematode parasites and owasionally are described for the tissue-invading larval stages of the nematodes and the c&odes. In t.he case of t.he trematodes it has been suggested that these so-called “histolytic enzymes” produced in the penetration glands may possibly aid in the escape of cercariae from the sporocyst (Faust and Hoffman, 1934) as well as assist cercariae in passing through the tissues, or in emerging from the molluscan host (Price, 1931). Furthermore Faust and Meleney (1924) state that the miracidia of Schistosoma jnponicum are capable of producing enzymes which digest away t,he mesenchymous tissues of the intermediate snail host and thus facilitate passage of the parasite. For the schistosomes of man it is believed (Girges, 1934) that t,he t)osic effects upon the definitive host may be due in part. t,o the passage of histolyt)ic enzymes from t,hc FUJIshell ink) t.hc sllrrounding Cssnes. It is tniracidium t,hrough the cdb also assumed t’hat this escaping enzyme may assist ilr the movement UI passage of schistosome eggs through the binding t’issues in which they have been deposited. ‘The opinions and statements contained herein are the private ones of the writer and are not to be construed as official or reflecting the views of the Navy Ikpnrt.mcnt or the Naval Service at Iargc. ? Lt., MCS, IJ. S. Navy. s The author wishes to cxprrss appreciation for :w3ist~:tncc given 1)~ Dr. hl. A. Stirewalt, N:~v:rl Rlcdical l
398
ROBERT
E. KIJNTZ
Recent interest in the enzymes or substances liberated by tissueinvading organisms has led to numerous studies relating to hyaluronidase and “spreading factors” @ran-Reynals, 1942). Since it had been demonstrated that hyaluronidase (an enzyme capable of disaggregating and depolymerizing hyaluronic acid, and thus a contributing factor to the spread of organisms through the connective tissue of skin) occurs in numerous bacterial organisms and in animal substances that encourage these organisms to penetrate or spread in the skin, it seemed appropriat,e to determine whether the so-called “spreading factor,” an indicator of the presence of hyaluronidase, was present in the schistosome cercariae. Several preliminary trials gave definit,e evidence t,hat a suspension of macerated cercariae did demonstrate a spreading property. This lead to the recognition of definite hyaluronidase act’ivity, the determination being made by the viscometric method (Levine et al, 1948). An abundance of material and the subsequent injections of cercari$ suspensions (8. munsoni) into the abdominal skin of rabbits at Cairo revealed even more pronounced spreading than did the earlier work at the Naval Medical Research Institute at Bethesda, Maryland. The present study reveals the extent of spreading as demonstrated by the injection of macerated cercariae of S. mansoni int,o white rabbits. MATERIALS
AND
~V~ETHODS
The spreading property or capacity of the cercarial suspension ww demonstrat.ed using an equal volume of Evans blue dye4 as an indicator. A concentrated mass of cercariae was placed in a small mortar and ground for several minutes to crush the cercariae and release the enzyme contents of the penetration glands. The bodies and tails of all cercariae were crushed and formed a sticky mass. Several drops of distilled water were added to remove t’he macerated cercariae from the mortar and to make a suspension. The latter was mixed with dye shortly before intradermal injection into the ventral or lateral abdomirnd skin of sh:~vetl S!.rian white rabbits. Infected ~iomphukviu boissyi were placed in beakers of tap water to collect the emerging cercariae. Snails were deprived of food for 24 to 36 hours prior to the collection of cercariae to reduce the fecal contamination that would other\vise occur during the Z- to 4-hour period of cercnrial emergence. One hour after the snails had been removed from the beakers the upper g of the cercarial suspension decanted and centrifuged. As a result the cercarial concentrate contained little or nor organic debris. The centrifuged cercariae were kept in the refrigerator until an adequate working stock of 3 to 5 ml had been obtained. Usually a No. 22 gauge Ilypodermic needle was used for t.hc intr:Ltlcrm:d i11jcct,ion of 0.25 to 1 .O ml of the ccrcarinl suspension with Il:v:r~~s l)lue tl~.c. Two con4 T-1824 (lye, 0.5% solution
in ampule,
W. R. Warm-r
:~ntl (lompat\~-.
tmls were usctl for each iujrctiou of ccrcwiar. Out con1lo1 cousisteti of equal parts of m;~ccrntrd snail fwrs mtl the blue cl!~. The secoutl coutrol WLSr~omx~l saline :oltl dye. .2 snail feces control evils ~n~ployrtl sinw ou occasiou cercnrid suspcusious cout:Cnrd :I bit of sn:lil frws :cntf its :~womp:~~lying Ix~ctrrial population. Thr latter I hr cztf~rrr of sp:1cling of sonif’ of ihc cwuld possibly wrount for, 0)‘ illc~~c:lsf~ wrc:tri:tl s:t~~~~~lm. The c~xtc~ntor tlvgrw of spreatliug \v:ts ~wortld for P:IC~I iIljcd iorl of cc:rc:wi:le :III~I it,s accom~~w~ying co~~trols, 1)~outlining t hr tly~ imprc~gmrtcxl :LIWLin the skiu 0112 Ikw; of onion skin t\.pirig lxtpc~r hcltl :rg:iiust t hr fxl)l)it Awas of spw:ttling uwr computed l:it tlr from I he liuc dr:k\vings 011thcbpapt‘r. I~wortlings \verc~matlr :rt the time of the irrl r:~drrw:il ir~trodu~tion of test Inilt~~ri:~Is:Ilrtl :tg:tin :litc>r 2, 4, s,
:i1rtl
24
hours.
I~ICSlT,TS
AKD
~hSC’r-SSIOS
There ~-as definite, and oftell impressive, e\Gleilc*r of sp~eadi~~g ii1 each of 26 suspellsioiis of macderated wrcariae and Evans blue dye after intradermal injection into laboratory raised rabbits (Fig. 1). Most. of the inje&ons wew made 011the sides of the rahl)it. 111 the majority of cases the dyed areas indicating t hr spread were cluite regular itr shape hut the progress of spreading \ITIS mow rapid \.elltro:lllteriorl~. SKISpeiisions of macerated cwcariae stored iii the refrigerator for sc~crnl \~~ks showed essentially the same cdnpwity for sprcatling as did thr freshly prepared suspensiolls. There \vas 110 rvitletlw of sprea,dillg \vith the saline cwntrols atlid only wwsiotral spread of limited 1jut I-aryitlg extent (2 to 4 t’imes area of origiic~l hl&) \vc~rv ol~sc~rvedfor the sil:iil fwcs cwltrols (I+‘, Fig. 1). The amomlt of spreading indkated 1)~ the prese~~w of the dye \vithitl t,he skin ranged from areas t\vo to three times the size of the origillal Itlet) up to ureas ilwrwscd hy a ratio of 30 to X. Sprrading did not reac~hits maximum mltil 18-24 hours folio\\-ilg injec+ioll. .Ilthough the llumhers of c~erwriae (10,0(H)-40,000 per injectioll) I\-ere only IYN~&IJ twtimated there appeared to he IIO prwise or dirwt relationship het\\.ceIl iiumhcr of c*ercwiae employed aiid the csteikt of sprentlitlg ohser\*cd. It must he noted ho\vc\-cr that the spreatlilg WIS greater ilr se\.eral itIstullcw I\-hell UIIUSII~II~ large c~uantities of wrwriae ww illtroduc~etl intradermall\-. This finding swms to pnrallrl that ohservrd by I,?\-itlc 4 al. (l!M) \vho otwrved a lack of c*orrelatioir lwt \veeti t~iizyme ac+ti\.ity :iilil cfcrraiktl c~oiic~c~irtl~xtio~i\\he~i Il~:ilrirotlidas~~ nc*ti\-it- \\-a~ cletcrmined by the \~iwometric~ assay method. I-Io\ve\-er F,I~~~Isat~d Stir-c&t (1!~52~ hy a ditierrnt tl~d perhaps mow c-ritiwl approwh have noted a tlirwt rrlatiwwhip txt\vctvl the tlumtrcr of cwwriw ctmployetl :UK~ the
400 volumetric:
l{OBERT
redwt~ion
of hyalurotlic+
E.
KI:hT7
,
avid c*apsules of a strain
beta-hemolytic stwptocwwi. Possibly a variation as \vit,h variation ill the illfwtiveness of difierent from t,he same sljails (Evatjs and Stirewalt, l%l),
of group
C
in enzyme act#ivity, batches of cercariae may be linked \I-ith
the physiological state or well being of the snail hosts from which the wwariae have emerged. It, is generally agreed that t’wo distinct phenomena are at work when a parasit,e swh as a svhist,osome vervaria passes through the dermal harrier of its host. The first step is a mec*harGal phenomenon hy whkh the parasite wti\-ely fowes or I~~rrow its way t,hrough the skin. It is del)a.table whether the initial rasping or vut,t,ing prwess, afiec+etl t>\r
Lk’lUCADING
FACTOR”
IN
S. M.ZNSONI
CElU’ARIAE
401
muscular driven spines or chitinized parts of the parasite’s body, is augmented by enzymes actually deposited at the surface of the skin. There is rather definite evidence (Brackett, 1940), however, that the second phase of ent.ry, i.e., passage through the skin and its connective tissue elemt~rtts is in great part dependent upon enzymatic activity. Our present kno\\,ledge relating IO the factors responsible for the physical-chemical passage of cercariae through tissues is very limited and references to t)he nature of “histolytic” enzymes, in large part, have been drawn from the fields of deduction and speculation. As it is sometimes implied, the chemical phase of cercarial penetration is probably dependent upon an enzyme complex. Possibly hyaluronidase is one of several substances produced in cercarial penetration glands to insure efficient passage of the organism through the various tissue elements that may be encountered. Supporting this poly-enzyme hypothesis is the fact that different species of cercsariae possess secretory or penetrat,ion gla.nds which demonstrate different staining affinities, thus indicating a probable difference in the chemical nature of their contents. For instance, two types of penetrat,ion glands (Gordon, Davey, and Peast,on, 1934; Shafi, 1932) have heen described repeatedly for the cercariae of S. rnaxsoni and S. hacmalobium. Recent work by Evans and Stirewalt (1952) further supports the possibility of an enzyme or hyaluronidase complex in schistosome ccrcariae. The finding of hyaluronidase in the secretions of trematode larvae would not be at all surprising since various enzymes (Brackett, 1940; Cort, 1950) have been post#ulated as being the products of cephalic, secretory, or penetration glands in various cercariae. Furthermore Bruni (fide, Dnrsn-Reynals, 1942) has demonstrated a spreading power in the &ract.s of Ancy1ostom.a duodenale I\-hich he attributes to the secretory cephalic and cervical glands, and varying degrees of spreading have been described for extracts of leeches, scorprions, etc. (Duran-Reynals, 1942). Although it is realized that hyaluronidase and “spreading factor” are not identical terms, the observations in this laboratory and reports by others (Levine et al., 1948; Evans and Stirewalt, 1952) certainly suggest, hynluronidasr as playitlg a contributory part in the chemical phsr of c:erc:nri:d I)ellct.f,:ltioll. ‘l’l~csc~ litltlings naturally lend themsc~lvrs to spc~c~ulatio~l\vi th regard to t,he rclntionships of hyaluronidase an(l ct~z.vmc: c:omplest:s 1~)pathological, immunological, and other condi bicms con~c~mit~antwith cercarial dermatitis.
402
ItOBERT
E. IilIiXTZ
SUMMARY
The demonstration of the spreading capacity or factor following the intradermal injection of macerated cercariae of S. mansoni in rabbits supports earlier evidence that hyaluronidase may be an important part of an enzyme-complex secreted by trematode cercariae. REFERENCES BRACKETT, S. 1940. Pathology
of schistosome dermatitis. Such. L>erma~o2.unrl Syphilol. 42, l-9. CORT, W. W. 1950. Studies on schistosome dermatitis. XI. Status of knowledge after more than twenty years. Am. J. Hyg. 52, 251-307. DURAN-REYNALS, F. 1942. Tissue permeability and the spreading factors in iItfection. Bacterial. Revs. 6, 197-252. EVANS, A. S., AND STIREWALT, M. A. 1951. Variations in infectivity of cercarisc of Schistosoma mansoni. Exptl. Z’arasitol. 1, 19-33. EVANS, 4. S., AND STIREWAIX, M. -4. 1952. Further studies on the demonstration of an enzymatic factor in cercariae of Schistosoma mansoni by the strepto-coccal decapsulation test. J. Parasitol. 38, (Suppl.) 33. FAUST, E. C., AND MELENEY, H. E. 1924. Studies on schist,osomiasis japonica. A ~1. J. Hyg. (Monogr. Ser.) 3, l-339. FAUST, E. C., ASD HOFFMAN, W. A. 1934. Studies on schistosomiasis mnnsoni in Puerto Rico. III. Biological studies. 1. The extra-mammalian phase of the life cycle. Puerto Xico J. I’ctblic Health l’rop. Med. 10, l-47. GIRGLS, R.. 1934. Schistosomiasis (Bilharziasis). John Bale and Sons, London GORDON, R. &I., DAVEY, T. H., .~NI) PEASTON, II. 1934. The transmission of human bilhnrzinsis in Sierra Leone, with an account of the life-cycle of t,he schistosomes concerned. S. mansoni and S. haernatobium. Ann. il’rop. Med. Parasitol. 27, 323419. LEVINE, M. D., GARZOLI, R. E., KUNTZ, It. F., AND KILLOUGII, J. H. 1948. On the demonstration of hyaluronidase in cercariae of Schistosoma mansoni. J. Parasitol. 34, 158-161. PRICE, H. F. 1931. Life History of Schistosomatium douthitti (Cort). :lm. J. HI/~. 13, 685-727. SHAFI, A. M. 1932. The secretory glands of the ccrcariac of S. haemulobizc?rl and 9. mansoni from Egypt. Ann. Trop. Med. Hyg. 26,7-22.
oj Helvlintholog2/,
E.
Factor” manson
in the
Iiuntz?J
U. S. Xaual Jledical Research Unit No. 3, American Edassy, Cairo, Egypt
(Submitted for publication,
9 October 1952)
General terms such as histolytic:, proteolytic and mucolytic enzymes, digestive juices and ferments, and penetration secretions, have been used loosely in referring to the chemical aids which augment the mechanical entry of tissue-penetrating parasites into t’heir hosts. These terms a;pear frequently in studies relating to the cercariae of trematode parasites and owasionally are described for the tissue-invading larval stages of the nematodes and the c&odes. In t.he case of t.he trematodes it has been suggested that these so-called “histolytic enzymes” produced in the penetration glands may possibly aid in the escape of cercariae from the sporocyst (Faust and Hoffman, 1934) as well as assist cercariae in passing through the tissues, or in emerging from the molluscan host (Price, 1931). Furthermore Faust and Meleney (1924) state that the miracidia of Schistosoma jnponicum are capable of producing enzymes which digest away t,he mesenchymous tissues of the intermediate snail host and thus facilitate passage of the parasite. For the schistosomes of man it is believed (Girges, 1934) that t,he t)osic effects upon the definitive host may be due in part. t,o the passage of histolyt)ic enzymes from t,hc FUJIshell ink) t.hc sllrrounding Cssnes. It is tniracidium t,hrough the cdb also assumed t’hat this escaping enzyme may assist ilr the movement UI passage of schistosome eggs through the binding t’issues in which they have been deposited. ‘The opinions and statements contained herein are the private ones of the writer and are not to be construed as official or reflecting the views of the Navy Ikpnrt.mcnt or the Naval Service at Iargc. ? Lt., MCS, IJ. S. Navy. s The author wishes to cxprrss appreciation for :w3ist~:tncc given 1)~ Dr. hl. A. Stirewalt, N:~v:rl Rlcdical l
398
ROBERT
E. KIJNTZ
Recent interest in the enzymes or substances liberated by tissueinvading organisms has led to numerous studies relating to hyaluronidase and “spreading factors” @ran-Reynals, 1942). Since it had been demonstrated that hyaluronidase (an enzyme capable of disaggregating and depolymerizing hyaluronic acid, and thus a contributing factor to the spread of organisms through the connective tissue of skin) occurs in numerous bacterial organisms and in animal substances that encourage these organisms to penetrate or spread in the skin, it seemed appropriat,e to determine whether the so-called “spreading factor,” an indicator of the presence of hyaluronidase, was present in the schistosome cercariae. Several preliminary trials gave definit,e evidence t,hat a suspension of macerated cercariae did demonstrate a spreading property. This lead to the recognition of definite hyaluronidase act’ivity, the determination being made by the viscometric method (Levine et al, 1948). An abundance of material and the subsequent injections of cercari$ suspensions (8. munsoni) into the abdominal skin of rabbits at Cairo revealed even more pronounced spreading than did the earlier work at the Naval Medical Research Institute at Bethesda, Maryland. The present study reveals the extent of spreading as demonstrated by the injection of macerated cercariae of S. mansoni int,o white rabbits. MATERIALS
AND
~V~ETHODS
The spreading property or capacity of the cercarial suspension ww demonstrat.ed using an equal volume of Evans blue dye4 as an indicator. A concentrated mass of cercariae was placed in a small mortar and ground for several minutes to crush the cercariae and release the enzyme contents of the penetration glands. The bodies and tails of all cercariae were crushed and formed a sticky mass. Several drops of distilled water were added to remove t’he macerated cercariae from the mortar and to make a suspension. The latter was mixed with dye shortly before intradermal injection into the ventral or lateral abdomirnd skin of sh:~vetl S!.rian white rabbits. Infected ~iomphukviu boissyi were placed in beakers of tap water to collect the emerging cercariae. Snails were deprived of food for 24 to 36 hours prior to the collection of cercariae to reduce the fecal contamination that would other\vise occur during the Z- to 4-hour period of cercnrial emergence. One hour after the snails had been removed from the beakers the upper g of the cercarial suspension decanted and centrifuged. As a result the cercarial concentrate contained little or nor organic debris. The centrifuged cercariae were kept in the refrigerator until an adequate working stock of 3 to 5 ml had been obtained. Usually a No. 22 gauge Ilypodermic needle was used for t.hc intr:Ltlcrm:d i11jcct,ion of 0.25 to 1 .O ml of the ccrcarinl suspension with Il:v:r~~s l)lue tl~.c. Two con4 T-1824 (lye, 0.5% solution
in ampule,
W. R. Warm-r
:~ntl (lompat\~-.
tmls were usctl for each iujrctiou of ccrcwiar. Out con1lo1 cousisteti of equal parts of m;~ccrntrd snail fwrs mtl the blue cl!~. The secoutl coutrol WLSr~omx~l saline :oltl dye. .2 snail feces control evils ~n~ployrtl sinw ou occasiou cercnrid suspcusious cout:Cnrd :I bit of sn:lil frws :cntf its :~womp:~~lying Ix~ctrrial population. Thr latter I hr cztf~rrr of sp:1cling of sonif’ of ihc cwuld possibly wrount for, 0)‘ illc~~c:lsf~ wrc:tri:tl s:t~~~~~lm. The c~xtc~ntor tlvgrw of spreatliug \v:ts ~wortld for P:IC~I iIljcd iorl of cc:rc:wi:le :III~I it,s accom~~w~ying co~~trols, 1)~outlining t hr tly~ imprc~gmrtcxl :LIWLin the skiu 0112 Ikw; of onion skin t\.pirig lxtpc~r hcltl :rg:iiust t hr fxl)l)it Awas of spw:ttling uwr computed l:it tlr from I he liuc dr:k\vings 011thcbpapt‘r. I~wortlings \verc~matlr :rt the time of the irrl r:~drrw:il ir~trodu~tion of test Inilt~~ri:~Is:Ilrtl :tg:tin :litc>r 2, 4, s,
:i1rtl
24
hours.
I~ICSlT,TS
AKD
~hSC’r-SSIOS
There ~-as definite, and oftell impressive, e\Gleilc*r of sp~eadi~~g ii1 each of 26 suspellsioiis of macderated wrcariae and Evans blue dye after intradermal injection into laboratory raised rabbits (Fig. 1). Most. of the inje&ons wew made 011the sides of the rahl)it. 111 the majority of cases the dyed areas indicating t hr spread were cluite regular itr shape hut the progress of spreading \ITIS mow rapid \.elltro:lllteriorl~. SKISpeiisions of macerated cwcariae stored iii the refrigerator for sc~crnl \~~ks showed essentially the same cdnpwity for sprcatling as did thr freshly prepared suspensiolls. There \vas 110 rvitletlw of sprea,dillg \vith the saline cwntrols atlid only wwsiotral spread of limited 1jut I-aryitlg extent (2 to 4 t’imes area of origiic~l hl&) \vc~rv ol~sc~rvedfor the sil:iil fwcs cwltrols (I+‘, Fig. 1). The amomlt of spreading indkated 1)~ the prese~~w of the dye \vithitl t,he skin ranged from areas t\vo to three times the size of the origillal Itlet) up to ureas ilwrwscd hy a ratio of 30 to X. Sprrading did not reac~hits maximum mltil 18-24 hours folio\\-ilg injec+ioll. .Ilthough the llumhers of c~erwriae (10,0(H)-40,000 per injectioll) I\-ere only IYN~&IJ twtimated there appeared to he IIO prwise or dirwt relationship het\\.ceIl iiumhcr of c*ercwiae employed aiid the csteikt of sprentlitlg ohser\*cd. It must he noted ho\vc\-cr that the spreatlilg WIS greater ilr se\.eral itIstullcw I\-hell UIIUSII~II~ large c~uantities of wrwriae ww illtroduc~etl intradermall\-. This finding swms to pnrallrl that ohservrd by I,?\-itlc 4 al. (l!M) \vho otwrved a lack of c*orrelatioir lwt \veeti t~iizyme ac+ti\.ity :iilil cfcrraiktl c~oiic~c~irtl~xtio~i\\he~i Il~:ilrirotlidas~~ nc*ti\-it- \\-a~ cletcrmined by the \~iwometric~ assay method. I-Io\ve\-er F,I~~~Isat~d Stir-c&t (1!~52~ hy a ditierrnt tl~d perhaps mow c-ritiwl approwh have noted a tlirwt rrlatiwwhip txt\vctvl the tlumtrcr of cwwriw ctmployetl :UK~ the
400 volumetric:
l{OBERT
redwt~ion
of hyalurotlic+
E.
KI:hT7
,
avid c*apsules of a strain
beta-hemolytic stwptocwwi. Possibly a variation as \vit,h variation ill the illfwtiveness of difierent from t,he same sljails (Evatjs and Stirewalt, l%l),
of group
C
in enzyme act#ivity, batches of cercariae may be linked \I-ith
the physiological state or well being of the snail hosts from which the wwariae have emerged. It, is generally agreed that t’wo distinct phenomena are at work when a parasit,e swh as a svhist,osome vervaria passes through the dermal harrier of its host. The first step is a mec*harGal phenomenon hy whkh the parasite wti\-ely fowes or I~~rrow its way t,hrough the skin. It is del)a.table whether the initial rasping or vut,t,ing prwess, afiec+etl t>\r
Lk’lUCADING
FACTOR”
IN
S. M.ZNSONI
CElU’ARIAE
401
muscular driven spines or chitinized parts of the parasite’s body, is augmented by enzymes actually deposited at the surface of the skin. There is rather definite evidence (Brackett, 1940), however, that the second phase of ent.ry, i.e., passage through the skin and its connective tissue elemt~rtts is in great part dependent upon enzymatic activity. Our present kno\\,ledge relating IO the factors responsible for the physical-chemical passage of cercariae through tissues is very limited and references to t)he nature of “histolytic” enzymes, in large part, have been drawn from the fields of deduction and speculation. As it is sometimes implied, the chemical phase of cercarial penetration is probably dependent upon an enzyme complex. Possibly hyaluronidase is one of several substances produced in cercarial penetration glands to insure efficient passage of the organism through the various tissue elements that may be encountered. Supporting this poly-enzyme hypothesis is the fact that different species of cercsariae possess secretory or penetrat,ion gla.nds which demonstrate different staining affinities, thus indicating a probable difference in the chemical nature of their contents. For instance, two types of penetrat,ion glands (Gordon, Davey, and Peast,on, 1934; Shafi, 1932) have heen described repeatedly for the cercariae of S. rnaxsoni and S. hacmalobium. Recent work by Evans and Stirewalt (1952) further supports the possibility of an enzyme or hyaluronidase complex in schistosome ccrcariae. The finding of hyaluronidase in the secretions of trematode larvae would not be at all surprising since various enzymes (Brackett, 1940; Cort, 1950) have been post#ulated as being the products of cephalic, secretory, or penetration glands in various cercariae. Furthermore Bruni (fide, Dnrsn-Reynals, 1942) has demonstrated a spreading power in the &ract.s of Ancy1ostom.a duodenale I\-hich he attributes to the secretory cephalic and cervical glands, and varying degrees of spreading have been described for extracts of leeches, scorprions, etc. (Duran-Reynals, 1942). Although it is realized that hyaluronidase and “spreading factor” are not identical terms, the observations in this laboratory and reports by others (Levine et al., 1948; Evans and Stirewalt, 1952) certainly suggest, hynluronidasr as playitlg a contributory part in the chemical phsr of c:erc:nri:d I)ellct.f,:ltioll. ‘l’l~csc~ litltlings naturally lend themsc~lvrs to spc~c~ulatio~l\vi th regard to t,he rclntionships of hyaluronidase an(l ct~z.vmc: c:omplest:s 1~)pathological, immunological, and other condi bicms con~c~mit~antwith cercarial dermatitis.
402
ItOBERT
E. IilIiXTZ
SUMMARY
The demonstration of the spreading capacity or factor following the intradermal injection of macerated cercariae of S. mansoni in rabbits supports earlier evidence that hyaluronidase may be an important part of an enzyme-complex secreted by trematode cercariae. REFERENCES BRACKETT, S. 1940. Pathology
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