 Assay development is an intrinsic part of drug and biological development. The current assay for anti-PRTX-100 antibodies depends on a very limited supply of serum available from individuals in early trials. It will be necessary to obtain adequate antisera to provide immunological reagents for this assay. It is not known whether the character of anti-PRTX-100 antibodies from volunteers is similar to those produced by patients with immunological disorders on cytotoxic therapy. Antisera will be developed in normal volunteers. The anti-PRTX-100 antibody assay will need to be standardized with a new anti-PRTX-100 antibody source compared to the present human reagent. 