IDIOTYPIC VACCINE FOR TREATMENT OF HUMAN B-CELL LYMPHOMA - CONSTRUCTION OF IGG VARIABLE REGIONS FROM SINGLE MALIGNANT B-CELLS

Immunoglobulin idiotypes (Id) of malignant B cells represent highly sp ecific markers which can be used for vaccination. PCR-amplification of immunoglobulin genes enables the rapid production of large amounts of Id vaccines. However, the separate amplification and subsequent recom bination of heavy and light chains can lead to a loss of the relevant Id. To preserve the original chain pairs, we used single malignant B c ells derived from an immunocytoma patient. Cytoplasm was extracted and the mRNA transcribed into cDNA. The VH and VL genes were then amplifi ed by PCR and cloned into a vector for expression in E. coli. Id produ ction was checked using an anti-Id mouse monoclonal Ab raised against the patient's tumor-specific IgG. One out of 3 constructs expressed th e relevant Id. Analysis of the first 31 light chain residues revealed an identical sequence for the malignant B cells' IgG and the recombina nt Id construct. Exchange of either the heavy or light chain with an u nrelated chain resulted in loss of the Id. An unrelated sequence deriv ed from the c-myc protein is coupled to the Id vaccine. The lymphoma p atient was shown to have Abs to the c-myc sequence This sequence there fore, increases the Id(+) Ab's antigenicity. CD spectroscopy showed an alpha helical structure for the c-myc epitope. In conclusion, a B-cel l lymphoma autovaccine was produced containing immunogenic sequences t hat do not alter the steric conformation of the tumor-specific Id. (C) American Society for Histocampatibility and Immunogenetics, 1997. Pub lished by Elsevier Science Inc.