Processing of HLA-class II invariant chain and expression of the p35 form is different in malignant and transformed cells.

A monoclonal antibody VCD-1, directed against the N-terminal intracellular part of the invariant chain (li) was used to show, by immunoprecipitation and Western blotting, the unprocessed and processed forms of li in chronic lymphocytic leukemia (CLL) cells, in Epstein-Barr virus-transformed normal lymphocytes (EBVL), and in cells of the Raji Burkitt's lymphoma cell line. Terminal glycosylation and sulphation of li in the Golgi apparatus was shown in Raji cells and not in EBVL. CLL lymphocytes contain a higher concentration of p35 li than do EBVL or Raji cells.