PROCESS FOR THE SEPARATION OF SPECIFIC IMMUNOGLOBULINS FROM STANDARD PLASMA AND THEIR USE FOR THERAPEUTIC TREATMENTS

Abstract: The process described permits the isolation of specific immunoglobulins from standard plasma by treatment of the Cohn's fraction II solution (obtained from standard plasma according to known methodology) by affinity chromatography.

Description: Process for the separation of specific immunoglobulins from standard plasma and their use for therapeutic treatments Field of Invention The present invention relates to a process for the production of specific immunoglobulins starting from standard plasma, in which a solution of Cohn's fraction II (obtained from standard plasma) is subjected to affinity chromatography under particular conditions. State of the Art It is known that standard immunoglobulins are normally obtained from standard plasma solutions (i.e. plasma obtained from healthy non-immunized donors) through a fractionating process at low temperature with alcohol (e.g. according to the Cohn's method) of the Cohn's fraction II (immunoglobulin enriched plasma fraction). Starting from this fraction and using classic or chromatographic purification techniques the desired immunoglobulin concentrates are obtained. Furthermore it is known that, when specific immunoglobulins are desired, in order to obtain their separation according to known techniques, it is necessary to use hyperimmune plasma (i.e. plasma supplied by immunized donors) enriched with the desired immunoglobulin. Infact, it is impossible to prepare specific immunoglobulins from standard plasma, since the specific immunoglobulin concentration in such a starting product is so low that it is practically impossible to prepare concentrates of suitable titre. The use of hyperimmune plasma, however, results in definitely higher costs compared to standard plasma; moreover, donor immunization is not allowed in certain countries, therefore the importation of hyperimmune plasma from abroad is required with a further increasing of costs and practical procedures. It should also be considered that the isolation of specific immunoglobulin from standard plasma using affinity chromatography requires the overcoming of numerous problems, in particular: a) definition of the quantities and the conditions for the attachment of the antigen to the resin; b) definition of the optimum attachment conditions of the desired immunoglobulin to the resin-antigen complex; c) definition of the optimum conditions for the attainment of the quantitative detachment of the desired immunoglobulin during the elution, for the collection of the same immunoglobulin. Detailed description of the invention The present invention solves the abovementioned problems, thus making possible the isolation of specific immunoglobulins starting from standard plasma, by adopting a method in which a solution of Cohn's fraction II, obtained from standard plasma, is subjected to affinity chromatography under opportune conditions. As mentioned above, the starting product for the process, according to the invention, is the Cohn's fraction II (obtained according to known techniques). Affinity chromatography is performed on chromatographic columns in which the activated matrix (resin) has been derivatized with an antigen, capable of recognizing and specifically binding to the desired immunoglobulin. According to the invention, for example, chemically stable active acrylic resins, capable of binding with sufficient stability to the immunoglobulins to be isolated, can be used. For example, resins in which the reactive function for the antigen attachment is represented by an oxyranic group are used for the above said purpose, since it reacts electroneutrally with the ligand with no byproduct release; an example of this resin type, useful for the present process is Eupergit C ® (manufactured by Rhom Pharma) or agarose resins derivatized with a hydrophilic spacer, terminally functionalized, as N-hydroxysuccinimid ester, which allows, in bland conditions, rapid and efficient coupling with antigens containing an aminic group, therefore allowing the formation of very stable covalent binding with respect to: denaturants, detergents, heat, solvents, acids and bases (pH range 2-11 ). These resins also possess excellent mechanical properties that allow elevated flow-rates, and are therefore especially useful for large scale purification processes. One example of this resin type is Affi-Prep10 ® (manufactured by Bio-Rad). In particular, the oxyranic group resins have proved preferable in the isolation of tetanus and diphtheria immunoglobulins; whereas agarose resins are preferred for the isolation of the whooping cough immunoglobulins. However, it is also obvious that other known resins possessing similar characteristics can be used according to the invention. The abovementioned resins are thus derivatized with a specific antigen for the desired immunoglobulin; such antigens are known and the resin derivatization is performed according to known techniques. Of particular importance is the maximum quantity of antigen that can be bound to the resin per unit volume in order to obtain maximum immunoglobulin yield, such a quantity does not necessarily correspond to the maximum quantity of antigen which can be theoretically bound to the resin per unit volume. For whooping cough, the antigen/resin ratio (expressed as mg of antigen per ml of resin) is between 0.8-3 (preferably 1.5); for tetanus the ratio is 8-16 (preferably 11 ); for diphtheria 3-5.5 (preferably 4.8). The resin is packed in a chromatography column; the column height/diameter ratio should preferably be between 1 :1 and 3:1 ; the column is then repeatedly washed with a phosphate buffer (pH 7.4). It is then loaded at a given rate, with the solution obtained by dissolving the Cohn's fraction II, in order to perform the chromatographic separation. The contact time between derivatized resin and solution should be approximately 14-18 hours. The column is then washed with a phosphate buffer solution of almost neutral pH (usually 7.0-7.6) to eliminate all the unbound proteins and then elution follows using a strogly acid glycin buffer (pH usually 2.0-3.0). The phosphate buffer is usually 0.1 M and comprises: 0.0031 M monobasic potassium phosphate and 0.0069 M bibasic potassium phosphate (pH 7.2); the glycin buffer consists of: 0.3 M glycin and HCI q.s. (pH of 2.5). In the case of the anti-tetanus immunoglobulin the glycin buffer preferably contains also dioxane 10% in volume (calculated in respect of the glycin volume). Operating in this way, it is possible to recover the immunoglobulins previously fixed to the substrate in a practically quantitative manner. Normally 12-16 beds are used for washing (preferably 14). The elution is conducted with a flow rate of between 3.5 and 7.5 cm/h. The collected eluate is then neutralized immediately with a phosphate buffer (pH 9) and 40% maltose. Finally the product is filtered against a suitable buffer solution, concentrated and lyophilized according to known techniques. Some examples are reproduced below to provide some indication of the process method according to the invention.. Example 1 Isolation of anti-whoopinq cough immunoglobulins Preparation of the Cohn's fraction II A set of frozen standard plasma bags, equivalent to 2,000 litres are thawed at a temperature of 2-3°C and cent fugated. The supernatant plasma is adjusted to a pH of 5.8-5.9 with pH 4 acetate buffer (consisting of: 21.7 g/l sodium acetate trihydrate and 48ml/l acetic acid ) and added with 96% ethyl alcohol at -18°C, so as to obtain a final concentration of 19% maintaining the plasma temperature at -5 to -7°C. The whole solution is left under stirring for 6 hours at -7°C and centhfugated. The precipitate (approx. 60 g/l) named Cohn's fraction I + II + III is collected. About 60kg of paste comprising the above said fraction I + II + III are suspended in water at a temperature of 4°C in a ratio of 1 kg of precipate for every 5lt of water. The solution pH is adjusted to 4.8 with 1 M phosphate buffer (pH 4). After about 2 hours contact time at a temperature of 2°C-4°C, the solution is further diluted with water at 4°C until a concentration of 15 litres/kg of paste is obtained. The solution pH is adjusted, under stirring, to 5.05-5.1 with phosphate buffer and topped up to a concentration of 17% with 96% ethylic alcohol. After contact whilst under stirring, for at least 6 hours, at a temperature of -1 °C the solution is subjected to centhfugation; the precipitate consists of the Cohn's fractions I + III. The supernatant is subjected to deep layer filtration and NaCI (3g/l) is added, pH adjusted to 7.25 with NaOH (0.3 N) and 96% ethylic alcohol is added up to a concentration of 15%. The suspension is left under stirring for at least 6 hours at 7°C and centhfugated. The collected precipitate (approx. 15g/l of plasma) is the Cohn's fraction II enriched with immunoglobulins (the yield calculated on the initial plasma is approx. 5kg of immunoglobulins per 1 ,000 I of plasma). Pre p aration of Standard Batches of Cohn's fraction II 4kg of the fraction II obtained as described above, are solubilized at a ratio 1 :6 in bibasic sodium phosphate buffer (0.1 M, pH 6.8) and filtered for 0.45μm. This clear solution is diafiltered, at constant volume, with uitrafiltration system using membranes K 100 (100,000 n.m.w) against three volumes of bibasic sodium phosphate buffer (0.1 M, pH 6.8). The final solution, adjusted to a concentration of 50g/l is filtered under sterile conditions and then divided into 20 aliquots of 1 ,200ml each. Purification of specific anti-whoopinq cough immunoglobulins using affinity chromatography a) Derivatizaton of the resin 1 ,100 ml of Affi-Prep 10 ® , prepared in accordance with the manufacturer's instructions, are added to 370 ml of whooping cough anatoxin at a proteic concentration of 2.7 mg/ml. The mixture is left under slow stirring for 3 hours at room temperature, and then left to rest overnight at 4°C. 40 ml of 1 M glycin buffer (pH 8) are added and the solution is left under slow stirring for 1 hour at room temperature. The mixture is filtered and washed with 5 volumes of 0.01 M phosphate buffer containing 0.15 M NaCI (pH 7.4). Protein dosage, performed on the resins washing solutions, reveals that 1 mg of protein has been bound for 1 ml of resin. The anatoxin/resin binding is stabilized by treatment with glutaraldehyde. A buffer containing 0.1 M phosphate, 0.5 M NaCI, 0.05% glutaraldehyde (pH 7.6) is added to the resin derivatized with anatoxin. It is left under slow stirring for 2 hours at room temperature and then 0.02 M glycin buffer is added to the final solution. The resin is then filter washed with 0.1 M phosphate buffer containing 0.02 M glycin. b) Affinity Chromatography The derivatized and stabilized resin (as described above) is packed into a column 11cm x 11 cm (d/h). Before every chromatography the column is treated with: - 15 beds of buffer T1 ( for the initial washing) - 7 beds of buffer T2 for the blank elution - 15 beds of buffer T1 for the conditioning Buffer T1 consists of: 0.01 M Phosphate buffer 0.15 M NaCI pH 7.4 Buffer T2 (glycin buffer) consists of : 0.3 M glycin HCI q.s. (pH 2.5) An aliquot of solution containing immunoglobulin (prepared as previously described) is loaded at a rate of 0.8 cm/h, for a contact time of 16 hours. It is washed with 15 beds of T1 buffer. Elution is performed at a flow rate of 6.7 cm/h with buffer T2, collecting the corresponding solutions at the registered elution peak. The eluate is collected and the pH is immediately neutralized with 1 M K2HPO4 (pH 9) and 40% maltose obtaining a solution of pH > 6 and 10% maltose. The eluate solution, diafiltered against 5 volumes of sterile and apyrogenic distilled water with uitrafiltration system with a membrane cut-off 100,000 n.m.w., is added with 22 g/l glycin and 3g/l NaCI maintaining the pH at 6.8±0.1. The chromatographic process carried out in this manner allows to recover 6,000- 6,500 UELISA/I of plasma (approx. 40% of the load). Example 2 Isolation of anti-tetanus immunoglobulins The Cohn's fraction II used as starting product is prepared as described in Example 1. Purification of specific anti-tetanus immunoglobulins using affinity chromatography a) De vatization of the resin 500g of Eupergit C ® are directly expanded in 3.5I of tetanic anatoxin solution at a protein concentration of 6.6 mg/ml and with a titrate expressed in flocculant unities/ml of approx. 2,700 Lf/ml. The mixture is left to rest at room temperature for 24 hours. Then the resin is recovered by filtration and washed repeatedly. The resin is derivatized with 11 mg of proteins and approx. 4,700 Lf/ml of resin, b) Affinity Chromatography A 11 x 21 cm (d/h) column is used containing 2 I of derived resin (as described previously). The column is treated with: - 7 beds of buffer T1 for the initial washing - 7 beds of buffer T3 for the blank elution - 7 beds of buffer T1 for the conditioning Buffer T3 consists of: 0.3 M glycin HCI q.s. (pH 2.5) 10% dioxan (V/V) An aliquot of the sample (prepared as previously deschbed) is loaded, approx. 27mg of total protein/ml of resin, at a rate of 0.7 cm/h, for a contact time of 16 hours. It is washed with 14 beds of buffer T1. Elution is performed at a flow rate of 3.5 cm/h with buffer T2, collecting the corresponding solutions at the registered elution peak. The eluate is collected and the pH is immediately neutralized with 1 M K2HPO4 (pH 9) and 40% maltose, obtaining solution at pH > 6 maltose final concentration 10%. The eluate solution, diafiltered against 5 volumes of sterile and apyrogenic distilled water with uitrafiltration system with a membrane cut-off 100,000 n.m.w., and concentrated so as to obtain at least 1 ,000 UELISA/ML is added with 22 g/l glycin and 3g/l NaCI maintaining the pH at 6.8 ± 0.1. The chromatographic process carried out in this manner allows to recover 3,000- 3,700 UELISA I of plasma (approx. 52% of the load). Example 3 Isolation of anti-diphtheria immunoglobulins The Cohn's fraction II used as starting product is prepared as described in Example 1. Purification of specific anti-diphtheria specific immunoglobulins using affinity chromatography a) Derivatization of the resin 2g of Eupergit C ® are directly expanded in 8 ml of diphtheric anatoxin solution (CRM 197) at a proteic concentration of 5.4 mg/ml and with a titrate (flocculants/ml) of approx. 1 ,874 Lf/ml. The derivatized resin is packed in a 16 x 45 mm (d/h) column. A total volume of 9 ml of resin in the column with 4.8 mg of total proteins/ml of resin, equal to 1 ,667 Lf/ml is obtained, b) Affinity Chromatography The column is treated with: - 7 beds of buffer T3 for the first washing - 7 beds of buffer T2 for the blank elution - 7 beds of buffer T3 for the conditioning The buffers T2 and T3 are as described previously. Portions of sample aliquots (prepared as previously described) are loaded, 28.5 mg of total proteins/ml of resin, at a rate of 0.1 17 cm/h, for a contact time of 16 hours. It is washed with 14 beds of buffer T1. Elution is performed at a flow rate of 7.5 cm/h with buffer T2, collecting the corresponding solutions at the registered elution peak. The eluate is collected in fractions of 6 ml each and immediately neutralized with 2 ml of 1 M K2HPO4 (pH 9) and 40% maltose, obtaining a solution of pH > 6, and 10% maltose. The yield obtained is 30% of the load. Obviously, the separated isolation processes of the various immunoglobulins described above can be carried out in sequence, transferring the eluate after the isolation of an immunoglobulin in a column and applying the conditions of eluation suitable for the separation of the following immunoglobulin and so forth.

Claims: CLAIMS 1. A process for the separation of specific immunoglobulins starting from standard plasma characterized in that a solution of the Cohn's fraction II (obtained from standard plasma) undergoes affinity chromatography using a neutral pH phosphate buffer as washing buffer and an acidic pH glycin buffer as an eluent for the specific immunoglobulin. 2. A process according to Claim 1 characterized in that activated matrixes are used, derivatized with a specific antigen for the desired immunoglobulin. 3. A process according to Claim 2 characterized in that the derivatized matrix is an activated resin of acrylic type or an agarose resin. 4. A process according to Claim 3 characterized in that the acrylic resin presents an oxyranic group as active function for the attachment of the antigen. 5. A process according to Claim 2 characterized in that the antigen/resin ratio is between 0.8 and 16 (mg antigen/ml resin). 6. A process according to Claim 5 characterized in that the contact between the derivatized resin and solution is 14 -18 hours. 7. A process according to Claim 6 characterized in that the specific immunoglobulin is eluted with a buffer solution having pH (2.0-3.0). 8. A process according to Claim 1 characterized in that the isolated immunoglobulin is the anti-whooping cough immunoglobulin. 9. A process according to Claim 6 characterized in that the utilized resin is an agarose resin. 10. A process according to Claim 9 characterized in that the antigen/resin ratio is 0.8-3 (mg antigen/ml resin). 11. A process according to Claim 1 characterized in that the isolated immunoglobulin is the anti-diphtheria immunoglobulins. 12. A process according to Claim 11 characterized in that the resin is an acrylic resin activated with oxyranic groups. 13. A process according to Claim 12 characterized in that the antigen/resin ratio is 3-5.5 (mg antigen/ml resin). 14. A process according to Claim 1 characterized in that the isolated immunoglobulin is anti-tetanus immunoglobulin. 15. A process according to Claim 14 characterized in that the resin is an acrylic resin activated with oxyranic groups. 16. A process according to Claim 15 characterized in that the antigen/resin ratio is 8-16 (mg antigen/ml resin). 17. A process according to Claims 8, 11 and 14 characterized in that the phosphate buffer consists of: 0.0031 M monobasic potassium phosphate 0.0069 M bibasic potassium phosphate pH 7.2. 18. A process according to Claims 8 and 11 characterized in that the elution buffer consists of: 0.3 M glycin HCI q.s., pH 2.5. 19. A process according to Claim 14 characterized in that the elution buffer consists of: 0,3M glycin HCI q.s., pH 2.5 10% dioxan V/volume of glycin. 20. A process for the separation of specific immunoglobulins starting from standard plasma characterized in that a Cohn's fraction II, obtained from standard plasma, is chromatographically processed in various steps, performed in sequences, wherein the column and elution conditions applyed for each step are those required for the desired immunoglobulin to be separated during the corresponding step.

Inventors: ARRIGHI SILVANA, NERI PAOLO, ARRIGHI, SILVANA, NERI, PAOLO
Applicants: ARRIGHI SILVANA, MINI RICERCA SCIENT TECNOLOG, NERI PAOLO, ARRIGHI, SILVANA, MINISTERO DELL'UNIVERSITA'E DELLA RICERCA SCIENTIFICA E TECNOLOGICA, NERI, PAOLO
Application year: 1998
Main classification: C07K16
IPC codes: C07K16