LOAN PURCHASE AGREEMENT

EXECUTION COPY

LOAN PURCHASE AGREEMENT

THIS LOAN PURCHASE AGREEMENT, dated June 3, 2005, is entered into by and among DLJ Mortgage Capital, Inc., a Delaware corporation (“Seller”), Credit Suisse First Boston Mortgage Acceptance Corp., a Delaware corporation (“Purchaser”), U.S. Bank National Association, as indenture trustee (the “Indenture Trustee”) and Irwin Whole Loan Home Equity Trust 2005-B (the “Issuer”):

WITNESSETH :

WHEREAS, Seller, in the ordinary course of its business acquires and originates mortgage loans and acquired or originated all of the mortgage loans listed on the Loan Schedule attached as Exhibit A hereto (the “Loans”);

WHEREAS, the parties hereto desire that: (i) the Seller sell the Loans to the Purchaser on the Closing Date and thereafter all Additional Balances relating to the Loans created on or after the Cut-off Date pursuant to the terms of this Loan Purchase Agreement together with the Basic Documents and (ii) the Seller make certain representations and warranties on the Closing Date;

WHEREAS, pursuant to the Trust Agreement, the Purchaser will sell the Loans and transfer all of its rights under this Loan Purchase Agreement to the Issuer on the Closing Date;

NOW, THEREFORE, for and in consideration of the sale of the Loans from Seller to the Purchaser on the date hereof, the Purchaser shall pay to Seller on the date hereof by wire transfer of immediately available funds the net proceeds to the Purchaser of the sale of the Notes, together with the Certificates, the parties hereto hereby agree as follows:

Section 1.    Transfer of Loans . (a) Seller hereby sells, transfers, assigns and otherwise conveys to Purchaser (A) the Loans and all Additional Balances thereafter arising, including the Mortgage Notes, the Mortgages, any related insurance policies and all other documents in the related Loan Files and including any Eligible Substitute Loans; (B) all pool insurance policies, hazard insurance policies, and bankruptcy bonds relating to the foregoing, and (C) all amounts payable after the Cut-off Date to the holders of the Loans in accordance with the terms thereof. In addition, Seller has delivered to the Purchaser or the Custodian, as directed by the Purchaser, the Loan Schedule and the documents listed on Exhibit C; provided, however, that the Purchaser does not assume the obligation under each Loan Agreement relating to a HELOC to fund Draws to the Mortgagor thereunder, and the Purchaser shall not be obligated or permitted to fund any such Draws, it being agreed that the Seller will retain the obligation to fund future Draws. Such conveyance shall be deemed to be made: (1) with respect to the Cut-off Date Principal Balances, as of the Closing Date; and (2) with respect to the amount of each Additional Balance created on or after the Cut-off Date, as of the later of the Closing Date and the date that the corresponding Draw was made pursuant to the related Loan Agreement, subject to the receipt by the Servicer of consideration therefor as provided in Section 3.16 of the Servicing Agreement and 3.05 of the Indenture.

(b)     Based on the Initial Certification of the Custodian, the Indenture Trustee acknowledges receipt by the Custodian of the documents identified in the Initial Certification and declares that the Custodian holds such documents and the other documents delivered to the Custodian constituting the applicable Loan Files, in trust for the exclusive use and benefit of all present and future Noteholders. The Indenture Trustee acknowledges that it or the Custodian will maintain possession of the Loans and the Loan Files in the State of Illinois, as directed by the Purchaser, unless otherwise permitted by the Rating Agencies.

(c)     The Indenture Trustee agrees to deliver on the Closing Date to the Purchaser and the Servicer an Initial Certification from the Custodian (to the extent received by the Indenture Trustee from the Custodian). Based on its review and examination, and only as to the documents identified in such Initial Certification, the Custodian, pursuant to the terms of the Custodial Agreement, will acknowledge that such documents appear regular on their face and relate to such Loan. Neither the Indenture Trustee nor the Custodian shall be under any duty or obligation to inspect, review or examine said documents, instruments, certificates or other papers to determine that the same are genuine, enforceable, recordable or appropriate for the represented purpose or that they have actually been recorded in the real estate records or that they are other than what they purport to be on their face; provided, however, that neither the Indenture Trustee nor the Custodian shall make any determination as to whether (i) any endorsement is sufficient to transfer all right, title and interest of the party so endorsing, as noteholder or assignee thereof, in and to that Mortgage Note or (ii) any assignment is in recordable form or is sufficient to effect the assignment of and transfer to the assignee thereof under the mortgage to which the assignment relates. Not later than 90 days after the Closing Date, upon receipt of a Final Certification from the Custodian provided for in the Custodial Agreement, the Indenture Trustee shall deliver to the Purchaser, the Seller and the Servicer such Final Certification, with any applicable exceptions noted thereon.

(d)     If, in the course of such review, the Indenture Trustee is notified by the Custodian that any document constituting a part of a Loan File does not meet the requirements of Exhibit C hereto, the Indenture Trustee shall cause the Custodian to list such as an exception in the Final Certification.

(e)     The Seller shall promptly correct or cure such defect within 90 days from the date it is so notified of such defect and, if the Seller does not correct or cure such defect within such period, the Seller shall either (i) substitute for the related Loan an Eligible Substitute Loan, which substitution shall be accomplished in the manner and subject to the conditions set forth in Section 2(d), or (ii) purchase such Loan within 90 days from the date the Seller was notified of such defect in writing at the Repurchase Price of such Loan if such defect materially and adversely affects the value of the related Loan or interests of the Noteholders or the Certificateholders; provided, however, that if the cure, substitution or repurchase of a Loan pursuant to this provision is required by reason of a delay in delivery of any documents by the appropriate recording office, then the Seller shall be given 270 days from the Closing Date to cure such defect or substitute for, or repurchase such Loan; and further provided, that the Seller shall have no liability for recording any Assignment of Mortgage in favor of the Indenture Trustee or for the Servicer’s failure to record such Assignment of Mortgage, and the Seller shall not be obligated to repurchase or cure any Loan as to which such Assignment of Mortgage is not recorded. The Indenture Trustee shall deliver written notice to each Rating Agency within

270 days from the Closing Date indicating each Mortgage (a) which has not been returned by the appropriate recording office or (b) as to which there is a dispute as to location or status of such Mortgage. Such notice shall be delivered every 90 days thereafter until the related Mortgage is returned to the Custodian. Any substitution shall not be effected prior to the additional delivery to the Indenture Trustee or the Custodian, of a Request for Release and the Loan File for any such Eligible Substitute Loan. The Repurchase Price for any such Loan shall be deposited by the Seller in the Payment Account on or prior to the Business Day immediately preceding such Payment Date in the month following the month of repurchase and, upon receipt of such deposit, the Custodian, pursuant to the terms of the Custodial Agreement, will release the related Loan File to the Seller and will execute and deliver at the Seller’s request such instruments of transfer or assignment prepared by the Seller, in each case without recourse, representation and warranty or as shall be necessary to vest in the Seller, or its designee, the interest of the Purchaser, the Issuer, and the Indenture Trustee in any Loan released pursuant hereto. It is understood and agreed that the obligation of the Seller to cure, substitute for or to repurchase any Loan which does not meet the requirements of this Section shall constitute the sole remedy respecting such defect available to the Indenture Trustee, the Purchaser and any Certificateholder against the Seller.

(f)     All of the Loan Files are being held pursuant to the Custodial Agreement. Notwithstanding anything to the contrary contained herein, the parties hereto acknowledge that the functions of the Indenture Trustee with respect to the custody, acceptance, inspection and release of the Loan Files pursuant to Sections 1 and 2 hereof shall be performed by the Custodian. In connection with the assignment of any Loan registered on the MERS® System, the Indenture Trustee shall cause, at the Servicer’s expense, as soon as practicable after the Closing Date, the MERS® System to indicate that such Loans have been assigned by the Seller to the Indenture Trustee in accordance with this Loan Purchase Agreement, the Trust Agreement and the Indenture for the benefit of the Noteholders by including (or deleting, in the case of Loans which are repurchased in accordance with this Agreement) in such computer files (a) the code “[IDENTIFY INDENTURE TRUSTEE SPECIFIC CODE]” in the field “[IDENTIFY THE FIELD NAME FOR INDENTURE TRUSTEE]” which identifies the Indenture Trustee and (b) the code “[IDENTIFY SERIES SPECIFIC CODE NUMBER]” in the field “Pool Field” which identifies the series of the Notes issued in connection with such Loans. Indenture Trustee agrees that it will not alter the codes referenced in this paragraph with respect to any Loan during the term of this Loan Purchase Agreement unless and until such Loan is repurchased in accordance with the terms of this Loan Purchase Agreement..

(a)     Representations and Warranties as to Seller . Seller represents and warrants to the Purchaser, the Indenture Trustee and the Issuer that as of the Closing Date:

(i)     Organization and Good Standing; Licensing . Seller is a company duly organized, validly existing and in good standing under the laws of the jurisdiction of its formation and has all licenses necessary to carry out its business as now being conducted, and is licensed and qualified to transact business in and is in good standing under the laws of its state of jurisdiction;

(ii)                  Power, Authority and Binding Obligations . Seller has the power and authority to make, execute, deliver and perform this Loan Purchase Agreement and all of the transactions contemplated under this Loan Purchase Agreement, and has taken all necessary action to authorize the execution, delivery and performance of this Loan Purchase Agreement. When executed and delivered, this Loan Purchase Agreement will constitute the legal, valid and binding obligation of Seller enforceable in accordance with its terms, except as enforcement of such terms may be limited by bankruptcy, insolvency or similar laws affecting the enforcement of creditors’ rights generally and by the availability of equitable remedies;

(iii)               No Conflicts . Neither the execution and delivery of this Loan Purchase Agreement, nor the consummation of the transactions herein contemplated hereby, nor compliance with the provisions hereof, will conflict with or result in a breach of, or constitute a default under, any of the provisions of any law, governmental rule, regulation, judgment, decree or order binding on Seller or its properties or the certificate of incorporation or by-laws of Seller, except those conflicts, breaches or defaults which would not reasonably be expected to have a material adverse effect on Seller’s ability to enter into this Loan Purchase Agreement and to consummate the transactions contemplated hereby;

(iv)                  No Consent . The execution, delivery and performance by Seller of this Loan Purchase Agreement and the consummation of the transactions contemplated hereby do not require the consent or approval of, the giving of notice to, the registration with, or the taking of any other action in respect of, any state, federal or other governmental authority or agency, except those consents, approvals, notices, registrations or other actions as have already been obtained, given or made and conveyance of the Loans by Seller are not subject to bulk transfer or any similar statutory provisions in effect in any applicable jurisdiction;

(v)     Enforceability . This Loan Purchase Agreement has been duly executed and delivered by Seller and, assuming due authorization, execution and delivery by the Purchaser, the Indenture Trustee and the Issuer, constitutes a valid and binding obligation of Seller enforceable against it in accordance with its terms (subject to applicable bankruptcy and insolvency laws and other similar laws affecting the enforcement of the rights of creditors generally) and general principles of equity;

(vi)                  No Litigation . There are no actions, litigation, suits or proceedings pending or threatened against Seller before or by any court, administrative agency, arbitrator or governmental body (i) with respect to any of the transactions contemplated by this Loan Purchase Agreement, (ii) on the sale of the Loans, or (iii) with respect to any other matter which in the judgment of Seller if determined adversely to Seller would reasonably be expected to materially and adversely affect Seller’s ability to perform its obligations under this Loan Purchase Agreement; and Seller is not in default with respect to any order of any court, administrative agency, arbitrator or governmental body so as to materially and adversely affect the transactions contemplated by this Loan Purchase Agreement; and

(vii)               Solvent . Seller does not believe, nor does it have any cause or reason to believe, that it cannot perform each and every covenant contained in this Loan Purchase Agreement. Seller is solvent and the sale of the Loans by it will not cause Seller to

become insolvent. The sale of the Loans by Seller is not undertaken with the intent to hinder, delay or defraud any of Seller’s creditors.

(b)     Representations and Warranties as to Loans . Seller hereby represents and warrants, as to each Loan, that the representations and warranties set forth on Exhibit B attached hereto are true and correct as of the Cut-off Date, except where otherwise indicated in Exhibit B.

(c)     Representations and Warranties as to Purchaser . Purchaser warrants and represents to, and covenants with, Seller that:

(i)     Purchaser is a corporation duly organized, validly existing and in good standing under the laws of the jurisdiction of its incorporation, and has all requisite corporate power and authority to acquire, own and purchase the Loans;

(ii)                  Purchaser has full corporate power and authority to execute, deliver and perform under this Loan Purchase Agreement, and to consummate the transactions set forth herein. The execution, delivery and performance by Purchaser of this Loan Purchase Agreement, and the consummation by it of the transactions contemplated hereby, have been duly authorized by all necessary corporate action of Purchaser. This Loan Purchase Agreement has been duly executed and delivered by Purchaser and constitutes the valid and legally binding obligation of Purchaser enforceable against Purchaser in accordance with its respective terms;

(iii)               To the best of Purchaser’s knowledge, no material consent, approval, order or authorization of, or declaration, filing or registration with, any governmental entity is required to be obtained or made by Purchaser in connection with the execution, delivery or performance by Purchaser of this Loan Purchase Agreement, or the consummation by it of the transactions contemplated hereby;

(iv)                  Purchaser understands that the Loans have not been registered under the 1933 Act or the securities laws of any state:

(v)     Purchaser is acquiring the Loans for investment for its own account only and not for any other person;

(vi)                  Purchaser considers itself a substantial, sophisticated institutional investor having such knowledge and financial and business matters that it is capable of evaluating the merits and the risks of investment in the Loans;

(vii)               Purchaser has been furnished with all information regarding the Loans that it has requested from Seller;

(viii)            Neither Purchaser nor anyone acting on its behalf has offered, transferred, pledged, sold or otherwise disposed of the Loans, an interest in the Loans or any other similar security to, or solicited any offer to buy or accept a transfer, pledge or other disposition of the Loans, any interest in the Loans or any other similar security from, or otherwise approached or negotiated with respect to the Loans, any interest in the Loans or any other similar security with, any person in any manner, or made any general solicitation by means of general advertising or in any other manner, or taken any other action which would constitute a

distribution of the Loans under the 1933 Act or which would render the disposition of the Loans a violation of Section 5 of the 1933 Act or require registration pursuant thereto, nor will it act, nor has it authorized or will it authorize any person to act, in such manner with respect to the Loans; and

(ix)                  Either: (A) Purchaser is not an employee benefit plan (“Plan”) within the meaning of section 3(3) of the Employee Retirement Income Security Act of 1974, as amended (“ERISA”) or a plan (also “Plan”) within the meaning of section 4975(e)(1) of the Internal Revenue Code of 1986 as amended (“Code”), and Purchaser is not directly or indirectly purchasing the Loans on behalf of, investment manager of, as named fiduciary of, as trustee of, or with assets of, a Plan; or (B) Purchaser’s purchase of the Loans will not result in a prohibited transaction under section 406 of ERISA or section 4975 of the Code.

(d)     Upon discovery by Seller or upon notice from Purchaser, the Issuer, the Owner Trustee, the Indenture Trustee or any Custodian, as applicable, of a breach of any representation or warranty of the Seller set forth in Section 2(a) above which materially and adversely affects the interests of