1、Designation: F 1984 99 (Reapproved 2008)Standard Practice forTesting for Whole Complement Activation in Serum by SolidMaterials1This standard is issued under the fixed designation F 1984; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revis
2、ion, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice provides a protocol for rapid, in vitroscreening for whole complement activating proper
3、ties of solidmaterials used in the fabrication of medical devices that willcontact blood.1.2 This practice is intended to evaluate the acute in vitrowhole complement activating properties of solid materialsintended for use in contact with blood. For this practice, thewords “serum” and “complement” a
4、re used interchangeably(most biological supply houses use these words synonymouslyin reference to serum used as a source of complement).1.3 This practice consists of two procedural parts. Proce-dureAdescribes exposure of solid materials to a standard lot ofhuman serum, using a 0.1-mL serum/13 x 100-
5、mm disposabletest tube. Cellulose acetate powders and fibers are used asexamples of test materials. Procedure B describes assaying theexposed serum for significant functional whole complementdepletion as compared to control samples.1.4 This practice does not address function, elaboration, ordepletio
6、n of individual complement components, nor does itaddress the use of plasma as a source of complement.1.5 This practice is one of several developed for theassessment of the biocompatibility of materials. Practice F 748may provide guidance for the selection of appropriate methodsfor testing materials
7、 for other aspects of biocompatibility.1.6 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.2. Referenced Documents2.1 ASTM Standards:2F 748 Practice for Selecting Generic Biological Test Meth-ods for Materials and Devices2.2 ISO
8、 Document:ISO 10993-4: Biological Evaluation of Medical Devices,Part 4: Selection of Tests for Interactions with Blood33. Terminology3.1 Abbreviations:3.1.1 Abantibody (hemolysin).3.1.2 BBSbarbital buffered saline.3.1.3 BBS-Gbarbital buffered salinegelatin.3.1.4 BBS-GMbarbital buffered salinegelatin
9、 metals.3.1.5 C8complement.3.1.6 EDTAethylenediaminetetraacetic acid, disodiumsalt: dihydrate.3.1.7 HShuman serum.3.1.8 PVDFpolyvinylidene fluoride.3.1.9 RBCred blood cell(s).4. Summary of Practice4.1 Solid material specimens are exposed to contact with astandard lot of complement under defined cond
10、itions (Proce-dureA). Exposed serum then is tested for significant functionalcomplement depletion compared to controls under identicalconditions (Procedure B).5. Significance and Use5.1 Inappropriate activation of complement by blood-contacting medical devices may have serious acute or chroniceffect
11、s on the host. This practice is useful as a simple,inexpensive screening method for determining functionalwhole complement activation by solid materials in vitro.5.2 This practice is composed of two parts. In Part A(Section 11), human serum is exposed to a solid material.Complement may be depleted b
12、y the classical or alternativepathways. In principle, nonspecific binding of certain comple-ment components also may occur. The alternative pathway candeplete later acting components common to both pathways,that is components other than C1, C4, and C3 (1).4In Part B(Section 12), complement activity
13、remaining in the serum afterexposure to the test material is assayed by classical pathway-mediated lysis of sensitized RBC.1This practice is under the jurisdiction ofASTM Committee F04 on Medical andSurgical Materials and Devices and is the direct responsibility of SubcommitteeF04.16 on Biocompatibi
14、lity Test Methods.Current edition approved Aug. 1, 2008. Published August 2008. Originallyapproved in 1999. Last previous edition approved in 2003 as F 1984 99 (2003).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual
15、Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.4The boldface numbers in parentheses refer to the list of reference
16、s at the end ofthis specification.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.3 Assessment of in vitro whole complement activation, asdescribed here, provides one method for predicting potentialcomplement activation by medical
17、materials intended forclinical application in humans when the material contacts theblood. Other test methods for complement activation areavailable, including assays for specific complement compo-nents and their split products (see X1.3 and X1.4).5.4 This in vitro test method is suitable for adoptio
18、n inspecifications and standards for screening solid materials foruse in the construction of medical devices intended to beimplanted in the human body or placed in contact with humanblood.6. Preparation of Buffers6.1 Buffers, are prepared according to detailed protocol (2).“Water” refers throughout
19、to distilled, endotoxin-free water.The use of barbital (veronal) buffer is recommended. Barbitalis a class IVregulated substance and requires a DEA(3) licensefor purchase. The use of other buffer systems, such as, TRIS, ispermissible if they have been demonstrated not to activatecomplement (4).6.2 5
20、X Stock BBS (barbital-buffered saline), is prepared byadding 20.75 g NaCl plus 2.545 g sodium barbital (sodium-5,5-diethyl barbiturate) to about 400 mL water. The pH isadjusted to 7.35 with 1 N HCl, then brought to a final volumeof 500 mL in a volumetric flask.6.3 Metals Solution, is prepared by mak
21、ing a 2.0 M solutionof MgCl2(40.66 g MgCl26H2O into 100 mL distilledendotoxin-free water), and a 0.3 M solution of CaCl2(4.41 gCaCl22H2O into 100 mL distilled endotoxin-free water), andcombining the two solutions 1:1 (v:v). These solutions arestable one month at 4C.6.4 BBS-GM Working Solution, is pr
22、epared daily, by dis-solving 0.25 g gelatin in 50 mL endotoxin-free distilled waterthat is gently heated and stirred. The gelatin solution is addedto 50 mL 5X stock BBS plus 0.25 mL metals solution, broughtup to about 200 mL, then adjusted to pH 7.35 (with1NHClor 1 N NaOH) before bringing the final
23、volume to 250 mL ina volumetric flask.6.5 BBS-G Working Solution, is prepared the same way, butthe addition of the metals solution is omitted.6.6 10X Stock EDTA (0.1 M disodium dihydrate EDTA),isprepared by adding 7.44 g disodium EDTA2 H2O to about 160mL water, adjusting the pH to 7.65 (with 1 N NaO
24、H or 1 NHCl), then bringing the volume to 200 mL in a volumetricflask.6.7 BBS-G-EDTA (to be used in preparing RBC beforebeing washed out), is prepared by adding 10 mL of stock 10XEDTA to 90 mL of BBS-G in a volumetric flask.7. Preparation of Sheep RBC7.1 Commercially-obtained sheep red blood cells (
25、RBC)preserved in Alsevers solution are stored at 4C. The cells arediscarded after eight weeks or when the supernatant from thesecond wash contains hemoglobin by visual inspection.NOTE 1All centrifugations are at 4C. Except where indicated, allreagents, tubes, and cell preparations are kept on ice.7.
26、2 Five mL of sheep RBC are centrifuged at 1 000xgfor10 min.7.3 The cell pellet is resuspended in 10 mL of coldBBS-G-EDTA and incubated for 10 min at 37C. The cells arecentrifuged, and the pellet resuspended in 10 mL of BBS-G-EDTA.7.4 The cells are centrifuged, the supernatant discarded(first wash),
27、and the pellet resuspended in 10 mL of coldBBS-GM. Repeat twice (total of three washes).7.5 Adjust cell count spectrophotometrically (where anabsorbance of 0.56 corresponds to 1.5 x 108sheep RBC/mL, ata wavelength of 412 nm and a 1.0-cm light path for 1 volumeof cells in BBS-GM plus 24 volumes of wa
28、ter) or count witha hemocytometer, preparing 10 mL of 1.5 x 108cells/mL incold BBS-GM.7.6 The washed, diluted RBC can be held on ice and usedfor at least 12 h.8. Absorption of Serum (Complement)8.1 The use of human complement is required since thereare species differences in the efficiency of comple
29、ment activa-tion and the test materials are to be used in humans. Humanserum suitable as a source of complement may be purchasedfrom biological supply houses, and generally, is labeled asreagent-grade complement.8.2 Human serum may be absorbed with sheep RBC inorder to remove naturally-occurring ant
30、i-sheep RBC hemolyticantibodies, though for most purposes, the amount of hetero-phile antibody in human serum is not enough to influence thereaction assuming the cells are optimally sensitized withhemolysin. The procedure is detailed in 8.3-8.8.8.3 Fresh human serum or a commercial lot of human seru
31、mis obtained and stored at 70C. Fresh serum is preferred aslyophilized complement often is not as active as fresh serum.8.4 The serum is thawed on ice or reconstituted (if lyo-philized) with ice-cold (4C) distilled endotoxin-free water.8.5 All manipulations are done on ice, with ice cold reagentsand
32、 cells; centrifugations are carried out at 1000xgat4C. Itis critical that this entire procedure be done in the cold to avoidactivation of complement in this step.8.6 Cold serum and cold, packed, washed sheep RBC aremixed, 0.1 mL RBC/2.5 mL serum, incubated for 10 min onice, then centrifuged at 1 000
33、 x g for 10 min at 4C. Thesupernatant is transferred carefully to a new container on ice.8.7 The procedure in 8.6 is repeated twice.8.8 The absorbed human serum is stored in 0.51.0-mLaliquots (convenient for one-experiment use), in cold snap-capmicrofuge tubes and kept at 70C until used. Aliquots sh
34、ouldbe thawed on ice, used on the day of thawing, and not berefrozen.9. Determination of Optimal Hemolysin Concentration9.1 Determination of optimal hemolysin concentration isnecessary in order to conserve expensive reagents and to avoidprozone effects. Commercial rabbit anti-sheep RBC serum(Hemolys
35、in) is obtained, thawed, or, if lyophilized, reconsti-tuted with distilled endotoxin-free water), heat-inactivated at56C for 30 min to inactivate the rabbit complement, aliquotedin convenient volumes, and stored at 70C until used.F 1984 99 (2008)29.2 To cold 13 x 100 mm disposable glass tubes, place
36、d ina rack in an ice-bath, 0.1 mLof washed sheep RBC at 1.5 x 108cells/mL is added. If statistical evaluation of the results isdesired, three replicate tubes for each condition should be used.Otherwise, duplicates or even single dilution tubes are suffi-cient. One set of three replicate tubes receiv
37、es only 0.1 mL ofcold BBS-GM/tube (no RBC control, for complement color).9.3 To the RBC-containing tubes, one set of three tubes gets1.1 mL cold distilled H2O/tube (total lysis control), anothergets 0.1 mL BBS-GM (no hemolysin control), and the othersets get 0.1 mLeach of 1:2 serial dilutions of hem
38、olysin (tests).Dilutions between 1:400 to 1:25 600 antibody are recom-mended, with two sets of 1:400. The no RBC control receives0.1 mL of additional BBS-GM.9.4 Each tube is mixed quickly by gentle shaking toresuspend cells, the rack is placed in a 37C water bath,incubated 10 min, then returned to t
39、he ice bath.9.5 One of the two sets of 1:400 antibody gets 1.0 mL ofcold BBS-GM (no-complement control). All other tubes be-sides the total lysis control set get 0.5 mL cold BBS-GM, then0.5 mL of absorbed human serum (complement) diluted 1:100or 1:200.NOTE 2For a particular lot of human serum, a 1:1
40、00 or 1:200 dilutionshould provide sufficient complement activity. Also, percent lysis in theno-hemolysin (complement only) control should not exceed 10 %. If lysiswith the 1:100 dilution of complement exceeds 10 %, use 1:200. If theno-hemolysin control still exceeds 10 %, a different lot of serum w
41、ill needto be tested.9.6 Tubes are shaken manually to suspend cells, then therack is incubated in a 37C water bath for 1h, and intermit-tently shaken to keep cells in suspension.9.7 At the end of 1h, the rack is placed on ice. The coldtubes then are centrifuged at 1 000 x g for 10 min at 4C, andthe
42、supernatants decanted to correspondingly numbered 13 x100-mm glass tubes.9.8 Absorbance of the supernatants is measured at 412 nm.Percent lysis is calculated for each test and control tube bysubtracting from the 412 nm absorbance the no RBC control(mean of the three replicate tubes), dividing by the
43、 total lysiscontrol value (mean of the three replicate tubes), and multi-plying by 100.% lysis 5test absorbance 2 no RBC control absorbancetotal lysis absorbance3 100(1)9.9 Final % lysis for each condition is expressed as mean 6standard deviation of the three % lysis values for each three-replicate
44、set.9.10 A titration curve is obtained by plotting the inverse ofthe hemolysin concentration versus % specific lysis. Twice theconcentration of hemolysin that is just on the plateau of thetitration curve is used for sensitizing RBC for subsequentassays (optimal hemolysin concentration). Hemolysin is
45、freshly diluted from stock each day of use.10. Whole Complement Titration to Determine OptimalSerum Dilution10.1 If statistical evaluation of results is desired, all condi-tions should be assayed in triplicate, using three 13 x 100disposable glass test tubes per condition. Otherwise, duplicatesor si
46、ngle tubes are sufficient. Tubes are numbered in advance.Conditions include total lysis, no complement (no C), tests(dilutions of human serumHS) with and without hemolysin,and no RBC (complement color control, at highest concentra-tion of serum used). All reagents, tubes, and manipulations aredone i
47、ce-cold, with tubes held in a rack in an ice slurry.10.2 Washed RBC are added to all tubes except no RBCtubes (0.1 mL/tube of a 1.5 x 108cells/mL suspension). NoRBC tubes get 0.1 mL cold buffer.10.3 Total lysis tubes get 1.1 mL distilled H2O. The no Cand test with hemolysin tubes get 0.1 mL optimal
48、hemolysin(see 9.10), and no RBC tubes get 0.1 mL cold BBS-GM. Alltubes are shaken to resuspend cells, incubated in a 37C waterbath for 10 min, and placed back on ice.NOTE 3Another acceptable procedure is to make up one large batchof hemolysin-sensitized erythrocytes to cover all the tests planned wi
49、thinone weeks time. These cells are made up at5x108/mL and are stored at4C. They are washed each time they are used, and if hemolysis occurs,new sensitized cells are prepared. These sensitized cells are ready to use,making the addition of hemolysin to each tube unnecessary, whichsimplifies the experiment. Unsensitized RBC can be used as controls fornonspecific lysis.10.4 To all but the total lysis tubes, a maximum volume of1.0 mL of cold BBS-GM is added, reduced by the amount ofdiluted serum (see 10.5), which will be added at a maximum0.5 m
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