Methods of Using Labeled Ligands Having Human CD4 Specificity

A method of making a diagnostic agent for analyzing in vivo a migration or a distribution pattern of human CD4-bearing cells in a human subject, said method comprising the steps of:

• obtaining a ligand having specificity for a human CD4 molecule, wherein the ligand is an antibody fragment or a recombinant antibody fragment, and wherein the antibody fragment is selected from the group consisting of:
• an F(ab′)2 fragment, an Fab′ fragment, and an Fab fragment of the antibody Max.16H5, and wherein the recombinant antibody fragment is selected from the group consisting of:
• an F(ab′) fragment, an Fab′ fragment, and an Fab fragment of the antibody Max.16H5;
• and
• attaching a label to the ligand, thereby forming a diagnostic agent.