Vol. 44, No. 3INFECTION AND IMMUNITY, June 1984, p. 702-7070019-9567/84/060702-06$02.00/0Copyright C 1984, American Society for Microbiology

Fungistatic and Fungicidal Activity of Human Parotid SalivaryHistidine-Rich Polypeptides on Candida albicans

JERRY J. POLLOCK,'* LAKSHMAN DENEPITIYA,' BRUCE J. MAcKAY,1 AND VINCENT J. IACONO2

Department of Oral Biology and Pathology,' and Department of Periodontics,2 State University ofNew York at StonyBrook, Stony Brook, New York 11794

Received 10 November 1983/Accepted 24 February 1984

Human parotid saliva histidine-rich polypeptides exerted antifungal activity against Candida albicans atconcentrations similar to the known antifungal activity of the imidazole antibiotics. Inhibition of bothgrowth and viability could be demonstrated by optical density monitoring and plating assays. Inhibition ofgrowth was observed to be greatest when the histidine-rich polypeptides were added to the inoculum beforeaddition to the growth media. However, complete inhibition by these polypeptides was still noted duringactive growth at turbidities of C. albicans corresponding to 106 CFU/ml. At higher cell densities, growthwas delayed but not halted under the experimental conditions investigated. Candidacidal activity wasobserved with both growing and nongrowing cells. With respect to the latter, reaction of cells in buffer withthe histidine-rich polypeptides for a period of 30 min resulted in killing of >90% of two different strains of C.albicans, whereas a third strain was found to be less susceptible. Moreover, the kinetics of loss of cellviability correlated with the loss of potassium from the cells. In addition to the histidine-rich polypeptides,hen egg white lysozyme, poly-L-lysine, and poly-L-histidine affected C. albicans. Both of the polyaminoacids completely inhibited the growth of the yeast whereas lysozyme was not as potent. Where delays ingrowth were observed for all of these agents, including the histidine-rich polypeptides, turbidities reachedthose of untreated controls after a 24-h period. Enhanced effects were noted if C. albicans was preincubatedwith these agents in 0.025 2-(N-morpholino)-ethanesulfonic acid buffer, pH 5.2, before growth in the yeastsynthetic medium.

In an accompanying paper (16), we have demonstrated anantibacterial role for the salivary histidine-rich polypeptides(HRPs). In this communication, we report for the first timethat these polypeptides are antifungal in that they inhibit thegrowth and viability of Candida albicans. In this dualcapacity, the salivary HRPs join a select group of com-pounds which have been demonstrated previously to beeffective antimicrobial agents.

Lehrer and colleagues in a series of publications (9, 15, 19,20) have examined the antibacterial and antifungal propertiesof human, rabbit, and guinea pig polymorphonuclear leuko-cyte and macrophage cationic proteins. From their observa-tions, these authors concluded that these cationic proteinswere significantly more fungicidal against Candida speciesthan they were bactericidal for a number of gram-positiveand gram-negative bacteria. Both the naturally present lacto-ferrin and myeloperoxidase, which are well-known antibac-terial agents, have been shown to either inhibit growth or killCandida species (12, 15). These same dual antimicrobialproperties which we further corroborate in this study havealso been reported for lysozyme (15, 21, 28). Among theantibiotics, the newly developed imidazole compounds, suchas miconazole and clotrimazole, are very potent antimycoticagents (10, 11, 26) which can also destroy bacterial species,for example, Staphylococcus aureus (24).The purpose of this article is to report our initial findings

on the effects of HRPs on laboratory strains of C. albicans.

MATERIALS AND METHODSBiochemicals. 2-(N-Morpholino)-ethanesulfonic acid

(MES) was obtained from Calbiochem, La Jolla, Calif.

* Corresponding author.

702

Ammonium phosphate, ammonium sulfate, potassium phos-phate, sodium chloride, and manganous sulfate were ac-quired from Fisher Scientific Co., Pittsburgh, Pa. Magne-sium sulfate, ferrous sulfate, zinc sulfate, copper sulfate,biotin, calcium pantothenate, pyridoxine, nicotinic acid,thiamine hydrochloride, meso-inositol, and hen egg whitelysozyme (HEWL; 3 x crystallized) were obtained fromSigma Chemical Co., St. Louis, Mo. Poly-L-lysine hydrobro-mide (average molecular weight, 2,700) and poly-L-histidine(average molecular weight, 10,300) were from Miles Labora-tories, Elkhart, Ind.

Salivary HRPs. HRPs were isolated and purified as amixture of polypeptides as described in an accompanyingpublication (17). For biological assays HRP stock solutionswere prepared gravimetrically and sterilized through 0.22-,um GSTF membrane filters (Millipore Corp., Bedford,Mass.).

C. albicans cultures. C. albicans 18804, 28517, and 28815were obtained from the American Type Culture Collection,Rockville, Md. Stock cultures grown to late log phase inyeast morphology broth (Difco Laboratories, Detroit, Mich.)were stored lyophilized in 2% skim milk (Difco). For routineuse, lyophilized cultures were grown at 37°C as a 1:50dilution in yeast synthetic medium (YSM) (5) to late logphase (optical density at 600 nm, 0.9; light path, 1 cm).Freshly grown cells were then inoculated as either 1:50 or1:100 dilutions in YSM (10 ml), and at the late log phase ofgrowth (optical density at 600 nm, 0.9) cells were harvestedby centrifugation at 2,100 x g for 15 min at 4°C in an IEC PR-6000 centrifuge (Damon/International Equipment Co., Need-ham Heights, Mass.) and washed two times in ice-colddistilled water. Cells were then suspended in MES buffer,pH 5.2, at an ionic strength of 0.025 to an optical density of0.2 at 600 nm (approximately 106 viable CFU/ml) immediate-ly before assays. All assays were repeated at least twice.

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ANTIFUNGAL PROPERTIES OF HRPs 703

Effect of preincubation of C. albicans with HRPs and otheragents on growth inhibition. Effect of preincubation wasassayed by determining the growth of C. albicans 18804 inYSM after a preincubation with various agents. In theseexperiments, the C. albicans strains in MES buffer weretreated with HRP (250 p.g/ml), HEWL (250 ,ug/ml), poly-L-histidine (100 p.g/ml), or poly-L-lysine (100 ,ug/ml) for 2 h. At0.1, and 2 h of preincubation, 100-pJl aliquots in duplicatewere removed aseptically from each incubation mixture andtransferred to tubes containing YSM (5 ml each) which wereeither free of or supplemented with the same agent (at thesame concentration) to which the cells had been preexposed.Tubes were incubated at 37°C, and growth patterns weredetermined by measuring the optical density at 600 nm.

Effect of HRP concentration on growth inhibition andviability of C. albicans. In these experiments, C. albicans18804 was not preexposed to the agents. Instead, cells weredirectly inoculated into tubes containing YSM supplementedwith HRP at S to 250 ,ug/ml. The tubes were then incubatedat 37°C for 48 h, and the optical density at 600 nm wasrecorded at 24 and 48 h. Also, to correlate turbidity levelswith viable counts of CFU, aliquots were removed at 24 hfrom each tube and serially diluted in the same medium, and100-,ul aliquots from appropriate dilutions were plated ontoyeast morphology agar (Difco). The plates were then incu-bated at 37°C aerobically for 48 h and CFU were counted.Selected colonies were examined for purity under a dissect-ing microscope and by the Gram reaction before countingthem.Growth inhibition by HRPs at different phases of the growth

cycle of C. albicans. A series of tubes containing YSM (5 mleach) were each inoculated with 100-,ul aliquots from asuspension of late-log-phase cells of C. albicans 18804 inMES buffer at an optical density of 0.2 at 600 nm. At varioustime intervals in the growth cycle, HRP (at either 50 or 250,ug/ml) was added and the growth was monitored at 600 nm.

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Viability studies with HRPs under nongrowing conditions.Late-log-phase C. albicans strains 18804, 28517, and 28815were suspended in MES buffer to an optical density of 0.2 at600 nm. Cell suspensions (1 ml) were then prepared with orwithout the addition of HRP (100 ,ug/ml) and were incubatedat 37°C for 30 min. At 0, 5, 15, and 30 min of the incubation,100-,ul aliquots were removed from each mixture and seriallydiluted in MES buffer, and 100 1.l from appropriate dilutionswas plated onto yeast morphology agar plates, which werethen incubated aerobically at 37°C for 48 h. The plates wereexamined under a stereomicroscope, and colonies weretested by the Gram reaction before counting.

Effect of HRPs on K+ release from C. albicans. K+ releasewas determined by using a K+-specific microelectrode(model MI-444; Microelectrodes, Inc., Londonderry, N.H.),which was standardized with KCl solutions ranging froml0-5 to 10-1 M. A late-log-phase C. albicans 18804 culturesuspended in MES buffer to an optical density of 0.2 at 600nm was used. To 1-ml aliquots of this suspension of cells,HRPs at 0, 5, 25, 50, 100, or 250 ,ug/ml were added, and K+release from the yeast cells (extracellular K+) was deter-mined at various time intervals during a 45-min incubation atroom temperature. Total cellular K+ was measured after acell suspension was incubated for 30 min in a boiling-waterbath (24). The total K+ released was calculated in terms ofpercentage of total cellular K+ released by using the follow-ing formula: {[K+ (extracellular in sample) - K+ (released inMES buffer)]/[K+ (total cellular by boiling) - K+ (releasedin MES buffer)]} x 100.

RESULTS

Growth inhibition of C. albicans 18804 by HRPs andHEWL. The standard error for all growth assays varied+ 10%. A number of observations can be stated based on theresults obtained in Fig. 1: (i) control growth of C. albicans

I

02 4 6 8 10 12 14 24 0 2 4 6 8 10 12 14 24Time of Incubation (Hours)

FIG. 1. Growth inhibition of C. albicans 18804 by HRPs and HEWL. See text for details. (A) No preincubation in low-ionic-strengthbuffer; (B) preincubation for 1 h in MES buffer (ionic strength, 0.025), pH 5.2, before incubation into fresh growth media. Symbols: 0, controlreaction mixture without additives; x, cells exposed initially to 250 p.g of HEWL per ml and then diluted 50-fold into fresh growth media in theabsence of HEWL; A, cells exposed initially to 250 ,ug of HEWL per ml and then diluted 50-fold into growth media containing 250 FLg ofHEWL per ml; 0, cells exposed initially to 250 i.g of HRP per ml and then diluted 50-fold into fresh growth media in the absence of HRP; A,cells exposed initially to 250 ,ug of HRP per ml and then diluted 50-fold into growth media containing 250 ,ug of HRP per ml.

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704 POLLOCK ET AL.

18804 remained the same irrespective of whether cells werepreincubated in MES buffer, pH 5.2, for 1 h before growth inYSM; (ii) however, preincubation increased the sensitivityof the cells to both HRPs and HEWL; (iii) under the sameconditions the HRPs were more effective than HEWL; (iv)for both HRPs and HEWL, supplementation of the mediawith these agents to increase their concentration causedmore dramatic inhibitory effects than when the media werenot supplemented; and (v) with or without preincubation,but with HRP supplementation in the growth media at aconcentration of 250 F.g/ml, a complete inhibition of growthwas noted during examination of the turbidity of cultures fora period of 24 h.

Effect of HRP concentration on growth inhibition of C.albicans 18804. Table 1 demonstrates that, at concentrationsof 25 pug ofHRP per ml or higher in YSM, there was virtuallycomplete inhibition of growth after a 24-h incubation period.At 10 ,ug of HRP per ml, a slight inhibition was noted. WhenHRP was not placed in the growth medium initially but wasadded to growing cells, the following observations werenoted (Fig. 2): (i) the inhibitory effect on growth was greatestat lower cell densities; (ii) the higher the cell density, thegreater the concentration required to inhibit growth; (iii)complete growth inhibition could be obtained for 24 h at celldensities of approximately 106 CFU/ml (optical density at600 nm, 0.2), using an HRP concentration of 250 ,ug/ml (Fig.2); (iv) inhibition of growth at this cell concentration (106CFU/ml) by 50 ,ug/ml was delayed and was not complete ascells reached optical densities of the control after a 24-hperiod; and (v) at still higher cell densities, there was noinhibition of growth at 50 ,ug of HRP per ml but there wasdelay in growth at 250 ,ug of HRP per ml.

Inhibition of viability of C. albicans by HRPs. Undergrowing conditions, loss of viability of C. albicans 18804correlated with inhibition of growth (Table 1). At concentra-tions of 25 jig of HRP per ml or higher, >99% killing of theyeast was observed when cells were plated after a period of24 h in the growth media. Under nongrowing conditions,>90% inhibition of viability of C. albicans 18804 was notedwith the tested concentration of 100 p.g ofHRP per ml after aperiod of 30 min (Table 2; Fig. 3). Compared with C.albicans 18804, C. albicans 28517 was more sensitive,whereas C. albicans 28815 was considerably more resistantunder these experimental conditions.

TABLE 1. Effect of HRPs on growth and viability of C. albicans18804

HRP concn OD_6_a CFU/mlb % Loss of(p.gml)hZCF/ viabilityc

0 (control) 1.4 1075 1.4 107 010 1.2 107 025 0.035 14 x 103 99.8850 0.018 73.6 x 102 99.9375 0.013 12.4 x 103 99.98100 0.01 73.6 x 102 99.93150 0.01 5.3 x 102 99.99250 0.005 11.1 x 102 99.99

a Optical density at 600 nm (OD16m) was measured after 24 h ofgrowth at 37°C in YSM.

b Determined after plating of sample aliquots from 24-h growthcultures onto yeast morphology agar and growing for an additional48 h at 37°C. Values are the average of duplicate determinations.

c Expressed as a percentage of the control.

0

0~~~~~~~~0

8 0.17Ej~~

.05-7

0~~~~~~~~~~~0.

+goo-°.O_ _O.o-~O-O-.o °

0 2 4 6 8 10 12 24

Time of Incubation (hours)FIG. 2. Effect of addition of HRPs to C. albicans 18804 during

the growth cycle. See text for details. Symbols: 0, normal growthcurve of C. albicans 18804 in YSM; 0, addition of 50 ,ug of HRP per

ml at time on growth curve designated by arrow ( * -*); A, 50 p.g ofHRP per ml at time indicated by arrow ( .... >); A, 250 p.g of HRPper ml at time indicated by arrow ( .... >); 0, 50 p,g of HRP per mlat time indicated by arrow (-->); *, 250 p.g of HRP per ml at timeindicated by arrow (-->).

Effect of HRPs on release of potassium from C. albicans18804. Figure 4 demonstrates that at 50 or 100 ,ug of HRP per

ml, there was >90% release of potassium from the cells aftera period of 30 min. The kinetics of release of potassiumcorrelated with the loss of cell viability of this strain (Table2; Fig. 3). At 250 Fg of HRP per ml, potassium release was

100% and concentrations of HRP as low as 5 ,ug/ml were

significantly more effective in promoting release comparedwith release of potassium from control cells. The latter wereobserved to spontaneously release potassium within the first30 s of incubation, and this was followed by a much slowerrelease over time.

Effect of poly-L-lysine and poly-L-histidine on growth of C.albicans 18804. The following observations were noted for

TABLE 2. Effect of HRPs on viability of C. albicans 18804 undernongrowing conditions

Time CFU/ml ± SEbof in- % Losscuba- of viabi-tion Control HRP exposed lityc

(min)a

0 9.6 x 105 1.3x105 11.4x105 1.0 X 1055 9.0 x 105 1.4 x 10 5.4 x 105 ±0.6 x 105 39.9

15 12.9 x 105 ± 1.6 x 105 18.1 x 104 ± 3.5 x 104 85.930 11.4 x 105 ± 2.4 x i05 8.0 x i04 ± 0.9 X 104 93.0

a Cells with or without a final concentration of 100 ,ug of HRP perml were suspended in 0.025 M MES buffer, pH 5.2. Aliquots werewithdrawn at the indicated times and were plated onto yeastmorphology agar.

b Determined in duplicate after 48 h of incubation at 37°C.c Expressed as a percentage of the control.

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ANTIFUNGAL PROPERTIES OF HRPs 705

lO0 membrane results in loss of essential biosynthetic metabo-K.\lites and in turn in progressive degradation of cellular

structures with ultimate cell death (8, 10, 11, 13). At lower90 concentrations, the imidazole antibiotics are fungistatic (10,

11) and are thought to interfere with sterol 14C-denmethyla-80 - tion biosynthesis (22).

The candidastatic and candidacidal activities reported in70\this communication have been obtained with a group of

70 ~ \ \ \ naturally occurring human salivary polypeptides character-ized to be histidine rich (17). We have also noted that these

v 60 a effects can be elicited by poly-L-histidine. At considerablyhigher molar concentrations than the HRPs, L-histidine itselfwas however without effect (data not shown), suggesting

50 * that in the case of the HRPs it is the peptide form which maybe important to the antifungal activity. Histidine with itsimidazole-containing moiety therefore may be a key amino

0) \ \acid to the body's defenses. Based on an average molecularweight of approximately 7,500 for the group of HRPs

30 - (MacKay et al., unpublished data), the IIRPs are active at10-5 M, which is within the range of the effective candidaci-

20 dal concentration of the imidazole antibiotics miconazoleand clotrimazole (10, 26).a~s_The effects of HRPs on growth inhibition are suggested to

10 - some extent to be dependent on the ionic strength sinceas preincubation in low-ionic-strength MES buffer increased

the potency of these polypeptides. Effects of ionic strength0 10 20 30 were noted in our bacteriostatic and bactericidal studies

Time of Incubation (minutes)FIG. 3. Comparison of inhibition of viability of three strains of

C. albicans by HRPs under nongrowing conditions. See text for 100 / __*_ _details. Symbols: 0, C. albicans 18804 (standard error [SE], see ./Table 2); A, C. albicans 28517 (SE, ±15.96%; error range, 7.79 to / *35.14%); 0, C. albicans 28815 (SE, ±13.62%; error range, 7.35 to 90 A-A-A A24.53%).

80 - iV - v,,~~~ _____

the effects of poly-L-lysine and poly-L-histidine on growth of 70 L AC. albicans 18804 (Fig. 5): (i) preincubation of cells in MESbuffer with these agents gave greater growth inhibition than *when cells were treated with the polyamino acids but z 601 A /directly inoculated into YSM; (ii) without supplementation E Aof these polyamino acids in the growth media, poly-L-lysine / ,was a more effective inhibitor than poly-L-histidine; (iii) '

50 11/ 7/under conditions of preincubation and without supplementa- ° Ltion, only poly-L-lysine caused complete inhibition of E- /growth; (iv) although poly-L-histidine was a potent inhibitorof growth under these conditions (without supplementation),cells reached turbidities of controls after 24 h; and (v) when di 30the concentration of polyamino acid was increased throughsupplementation of either poly-L-histidine or poly-L-lysine inthe media, complete inhibition of growth was noted irre- 20spective of whether preincubation of cells in MES bufferbefore inoculation in synthetic medium was carried out. 10

IDSCUSSION

Imidazole antibiotics for the treatment of fungal diseases 0 1 2 5 15 25 35 45have become available commercially within the last 15years. These antibiotics have been reported to disrupt the Time of Incubotion (minutes)permeability of the cell membrane, alter glucose utilization FIG. 4. Effect of HRPs on potassiim release from C. albicansin the cell, and impair amino acid uptake (11, 27). It has been 18804. See text for details. Symbols: 0, cohtrol reaction mixture infurther suggested that the imidazoles interact with unsaturat- MES buffer; 0, cells exposed to 5 ,ug of HRP per ml in MES buffer;ed phospholipids in the cell membrane, thereby altering the V, 25 ,ug of HRP per ml; A, 50 ,ug of HRP per ml: *, 100 jig of HRPpermeability of the membrane (27). Interaction at the cell per ml; *, 250 ,ug of HRP per ml.

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E

C 20

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Al

.01A

0 2 8 l0 2~ 14 24

Time of Incubation (Hours)

FIG. 5. Growth inhibition of C. albicans 18804 by poly-L-histi-dine and poly-L-lysine. See text for details. Symbols: 0, controlreaction mixture without additives;*, cells initially exposed to 100,ug of poly-L-histidine per ml and then diluted 50-fold directly intofresh growth media;O, cells initially exposed to 100 p.g of poly-L-histidine and then preincubated for 1 h in MES buffer (ionicstrength, 0.025), pH 5.2, before 50-fold dilution and incubation ingrowth media; A, cells initially exposed to 100,ug of poly-L-lysineand then diluted 50-fold into fresh growth media; A, cells initiallyexposed to 100,ug of poly-L-lysine and then preincubated for 1 h inMES buffer before 50-fold dilution and incubation in growth media;0, initial exposure to 100 ,ug of either poly-L-histidine or poly-L-lysine per ml with or without preincubation but with supplementa-tion of 100 p.g of poly-L-histidine or poly-L-lysine per ml in thegrowth media.

reported in an accompanying article (16), but these polypep-tides appear to be very different in this respect from the humanneutrophil cationic proteins (9). The latter markedly losetheir inhibitory ability as the ionic strength of the reactionmixture is increased. Moreover, if the HRPs were includeddirectly in YSM, preincubation in MES buffer was found notto be necessary as growth and viability were completelyinhibited. Our observation that the HRPs were more effec-tive at lower cell densities is consistent with the interpreta-tion of a higher agent to cell concentration (24). Our resultssupport the studies of Van Den Bossche and co-workers (26)which demonstrate that the imidazole antibiotics act on more

rapidly dividing cells. As cells move further into the logphase, they are less susaeptible to the killing action of theimidazole antibiotics (26) and also to the lytic effect of theantifungal agent echinocandin (5).

Fungistatic and fungicidal effects have also been observedfor leukocyte and macrophage cationic proteins (9, 19).These proteins appear to be more effective against Candidaspecies than they are against a variety of tested bacteria.This interpretation might also be applied to the HRPs(compare studies of HRP with Streptococcus mutans [16]),although further investigations would be required to estab-lish possible differences in activity. In the case of the

leukocyte cationic proteins, fungicidal activity is suggested

to be dependent on the cationic nature of the proteins and on

the quantity of adsorbed agent. The basic nature of the

HRPs, in addition to the structure of the histidine residue,would also seem to be important as these molecules arehighly cationic in polyacrylamide gel electrophoresis (17).Both HEWL and poly-L-lysine were effective against Candi-da species in this system, although lysozyme was notcandidacidal even at high concentrations. Other proteins,including basic proteins, have been reported previously todegrade C. albicans (18, 28).

Candidacidal activity was noted with three laboratorystrains of C. albicans, although it is not clear why the strainsdiffered in their susceptibility to the HRPs. C. albicans 18804was used for most of the experiments and was found to beinhibited in its viability under both growing and nongrowingconditions. Similar to the findings noted with the imidazoleantibiotics (11, 24), loss of viability also correlated with lossof potassium from the cells, suggesting possible HRP dam-age at the cell membrane. We have previously demonstratedthat the HRPs alter the membrane permeability of S. mutansBHT (B. MacKay, V. Iacono, B. Baum, and J. Pollock, J.Dent. Res. 58:A257, 1979).

C. albicans is a yeastlike fungus present as part of thenormal flora of the human mouth (1, 7, 14). When itproliferates in the oral cavity it causes a condition called oralcandidiasis (14). A very common situation in which oralcandidiasis is most often seen is chronic atrophic candidosis,more commonly known as denture stomatitis (3, 4, 23). Ithas been suggested that C. albicans must be eliminated onboth the mucosa and the acrylic surface of the dentures tohalt the disease process, although recurrences are frequentbecause denture patients find it uncomfortable and embar-rassing to remove their dentures for cleansing purposes (3, 6,25). The latter has been suggested to create a problem ofsalivary access (2) which in turn may give rise to theinfection since saliva contains several nonimmune hostdefense substances known to retard the growth of fungi invitro. From the results described here, it is tempting tospeculate that the salivary HRPs represent one class ofnaturally occurring compounds capable of exerting potentantifungal effects in vivo. Their role, if any, in the controland prevention of oral candidiasis remains to be elucidated.

ACKNOWLEDGMENTSThis work was supported by Public Health Service grant DE-

04296 from the National Institute of Dental Research and byBiomedical Research Support Grant 2S07RR0577808.

LITERATURE CITED

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2. Budtz-Jorgensen, E. 1974. The significance of Candida albicansin denture stomatitis. Scand. J. Dent. Res. 82:151-190.

3. Budtz-Jorgensen, E. 1978. Clinical aspects of Candida infectionin denture wearers. J. Am. Dent. Assoc. 96:474-479.

4. Budtz-Jorgensen, E., A. Stenderup, and M. Grabowski. 1975. Anepidemiologic study of yeasts in elderly denture wearers. Com-munity Dent. Oral Epidemiol. 3:115-119.

5. Cassone, A., R. E. Mason, and 0. Kerridge. 1981. Lysis ofgrowing yeast-form cells of Candida albicans by echinocandin:a cytological study. Sabouraudia 19:97-110.

6. Davenport, J. C. 1970. The oral distribution of Candida indenture stomatitis. Br. Dent. J. 129:151-160.

7. Denepitiya, J. L., and I. Kleinberg. 1982. A comparison of themicrobial compositions of pooled human dental plaque andsalivary sediment. Arch. Oral. Biol. 27:739-745.

8. DeNollin, S., and M. Bargers. 1974. The ultrastructure ofCandida albicans after in vitro treatment with miconazole.Sabouraudia 12:341-351.

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ANTIFUNGAL PROPERTIES OF HRPs 707

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10. Iwata, K., Y. Kanda, H. Yamaguchi, and M. Osumi. 1973.Electron microscopic studies on the mechanism of action ofclotrimazole on Candida albicans. Sabouraudia 11:205-209.

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12. Kirpatrick, C. H., I. Green, R. R. Rich, and A. L. Schade. 1971.Inhibition of growth of Candida albicans by iron-unsaturatedlactoferrin: relation to host-defense mechanisms in chronicmucocutaneous candidiasis. J. Infect. Dis. 124:539-544.

13. Kobayashi, G. S., and G. Medoff. 1977. Antifungal agents:recent developments. Annu. Rev. Microbiol. 31:291-308.

14. Lehner, T. 1967. Oral candidiasis. Dent. Pract. Dent. Rec.17:209-216.

15. Lehrer, R. I., K. M. Ladra, and R. B. Hake. 1975. Nonoxidativefungicidal mechanisms of mammalian granulocytes: demonstra-tion of components with candidacidal activity in human, rabbit,and guinea pig leukocytes. Infect. Immun. 11:1226-1234.

16. MacKay, B. J., L. Denepitiya, V. J. Iacono, S. B. Krost, andJ. J. Pollock. 1984. Growth-inhibitory and bactericidal effects ofhuman parotid salivary histidine-rich polypeptides on Strepto-coccus mutans. Infect. Immun. 44:695-701.

17. MacKay, B. J., J. J. Pollock, V. J. Iacono, and B. J. Baum.1984. Isolation of milligram quantities of a group of histidine-rich polypeptides from human parotid saliva. Infect. Immun.44:688-694.

18. Niedermeyer, W. 1975. Effect of cytochrome C and peroxidaseon the plasmalemma of the yeast cell wall (Candida utilis).Cytobiologie 10:485-490.

19. Patterson-Delafield, J., R. J. Martinez, and R. I. Lehrer. 1982.Microbicidal cationic proteins in rabbit alveolar macrophages: apotential host defense mechanism. Infect. Immun. 30:180-192.

20. Patterson-Delafield, J., D. Szklarek, R. J. Martinez, and R. I.Lehrer. 1981. Microbicidal cationic proteins of rabbit alveolarmacrophages: amino acid composition and functional attributes.Infect. Immun. 31:723-731.

21. Poliock, J. J., H. Goodman, P. K. Elsey, and V. J. Iacono. 1983.Synergism of lysozyme, proteases and inorganic monovalentanions in the bacteriolysis of Streptococcus mutans GS5. Arch.Oral Biol. 28:865-871.

22. Pye, G. W., and M. S. Marriott. 1982. Inhibition of sterol 14Cdemethylation by imidazole-containing antifungals. Sabourau-dia 20:325-329.

23. Renner, R. P., M. Lee, L. Andors, and T. F. McNamara. 1979.The role of C. albicans in denture stomatitis. Oral Surg. OralMed. Oral Pathol. 47:323-328.

24. Sud, I. J., and D. S. Feingold. 1q82. Action of antifungalimidazoles on Staphylococcus aureus. Antimicrob. Agents Che-mother. 22:470-474.

25. Tarbet, W. J. 1982. Denture plaque: quiet destroyer. J.Prosthet. Dent. 48:647-652.

26. Van Den Bossche, H., G. Willemsen, and J. M. Van Cutsem.1975. The action of miconazole on the growth of Candidaalbicans. Sabouraudia 13:63-73.

27. Yamaguchi, H. 1978. Protection by unsaturated lecithin againstthe imidazole antimycotics, clotrimazole and miconazole. Anti-microb. Agents Chemother. 13:423-426.

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