Abstract: Disclosed are domain antibodies that monovalently bind CD28. Domain antibodies that are monovalent for binding of CD28 can inhibit CD28 activity. In one aspect, a domain antibody consists of or comprises a single immunoglobulin variable domain that specifically binds and antagonizes the activity of CD28, in an aspect, without substantially agonizing CD28 activity. In another aspect, the domain antibody is a human domain antibody. The disclosure further encompasses methods of antagonizing CD80 and/or CD86 interactions with CD28 in an individual and methods of treating diseases or disorders involving CD80 and/or CD86 interactions with CD28, the methods involving administering a domain antibody to the individual.

Abstract: Disclosed are domain antibodies that monovalently bind CD28. Domain antibodies that are monovalent for binding of CD28 can inhibit CD28 activity. In one aspect, a domain antibody consists of or comprises a single immunoglobulin variable domain that specifically binds and antagonizes the activity of CD28, in an aspect, without substantially agonizing CD28 activity. In another aspect, the domain antibody is a human domain antibody. The disclosure further encompasses methods of antagonizing CD80 and/or CD86 interactions with CD28 in an individual and methods of treating diseases or disorders involving CD80 and/or CD86 interactions with CD28, the methods involving administering a domain antibody to the individual.

Abstract: The invention relates to antibody polypeptides that monovalently bind CD40L. Antibody polypeptides that are monovalent for binding of CD40L can inhibit CD40L activity while avoiding potential undesirable effects that can occur with antibodies capable of divalent or multivalent binding of DC40L. In one aspect, a monovalent anti-CD40L antibody polypeptide consists of or comprises a single immunoglobulin variable domain that specifically binds and antagonizes the activity of DC40L, preferably without substantially agonizing CD40 activity. In another aspect, the monovalent anti-CD40L antibody polypeptide is a human antibody polypeptide. The invention further encompasses methods of antagonizing CD40/CD40L interactions in an individual and methods of treating diseases or disorders involving CD40/DC40L interactions, the methods involving administering a monovalent anti-CD40L antibody polypeptide to the individual.

Abstract: Disclosed are domain antibodies that monovalently bind CD28. Domain antibodies that are monovalent for binding of CD28 can inhibit CD28 activity. In one aspect, a domain antibody consists of or comprises a single immunoglobulin variable domain that specifically binds and antagonizes the activity of CD28, in an aspect, without substantially agonizing CD28 activity. In another aspect, the domain antibody is a human domain antibody. The disclosure further encompasses methods of antagonizing CD80 and/or CD86 interactions with CD28 in an individual and methods of treating diseases or disorders involving CD80 and/or CD86 interactions with CD28, the methods involving administering a domain antibody to the individual.