1 EXHIBIT 10.1 WAIVER OF REGISTRATION RIGHTS Immusol, Inc. 3050 Science Park Road San Diego, CA 92121 Attention: Tsvi Goldenberg Re: Public Offering of Common Stock of Immusol, Inc. Dear Mr. Goldenberg: In consideration of the proposed initial underwritten public offering of Common Stock of Immusol, Inc., a California corporation (the "Company"), to be managed by PaineWebber Incorporated, Needham & Company, Inc. and Sutro & Co. Incorporated (collectively, the "Representatives"), expected to be consummated on or prior to the end of August 1996 (the "Public Offering"), the undersigned hereby waives, solely with respect to the Public Offering, (i) the Investors' rights under that certain Amended and Restated Shareholder Rights Agreement dated May 3, 1995, between the Company and the Investors listed on Exhibit A thereto (the "Shareholder Agreement") to register and sell Registrable Securities, as defined in the Shareholder Agreement, as part of the Public Offering, and (ii) the requirement to notify the Investors of the Public Offering as set forth in the Shareholder Agreement. Dated: June 25, 1996 Very truly yours, BANKAMERICA VENTURES By: /s/ Anchie Kuo --------------------------------- Name Managing Director ---------------------------------- Title