Abnormal association between invariant chain and HLA class II alpha and beta chains in chronic lymphocytic leukemia.

We have previously shown that peripheral blood lymphocytes from patients with chronic lymphocytic leukemia (CLL) express increased amounts of the minor p35 form of class II invariant chain (Ii) relative to the major p33 form. In this report we demonstrate in Western blots that in CLL lymphocytes, but not in normal or Epstein-Barr virus-transformed normal lymphocytes, p35 and p33 Ii form sodium dodecyl sulfate (SDS)-resistant complexes with class II alpha and beta chains and that these complexes form an abnormally large proportion of the total class II molecules. Others have shown that stable SDS-resistant alpha-beta complexes are only formed upon binding of exogenous antigenic peptides for presentation at the cell surface.

Basic fibroblast growth factor antagonizes transforming growth factor beta-mediated erythroid differentiation in K562 cells.

Basic fibroblast growth factor (bFGF) and transforming growth factor-beta 1 (TGF-beta) have both been shown to act on hematopoietic progenitor cells. bFGF is a hematopoietic cytokine that acts on progenitor cells in concert with other cytokines to promote their proliferation. TGF-beta induces erythroid differentiation in K562 cells.

Site-directed mutagenesis of the synthetic Erythrina trypsin/tissue plasminogen activator (tPA) inhibitor encoding-gene to compare the interaction of Erythrina and soybean trypsin inhibitor with tPA.

Erythrina trypsin inhibitor (ETI) has good structural and sequence homology with soybean trypsin inhibitor (STI). However, STI does not inhibit tPA. From the three-dimensional structure of ETI it was known that the N-terminus of the molecule forms a finger-like structure stabilized by hydrogen bonds and hydrophobic interactions.

Synthesis and expression of a gene coding for Erythrina trypsin inhibitor (ETI).

A gene coding for Erythrina trypsin inhibitor (ETI) was designed, based on the published N-terminal sequence of the protein, and synthesized by an oligonucleotide-directed single strand break-repair mechanism. Direct expression from the expression vector pBtac1 was unsuccessful. A construct, encoding an extended methionyl N-terminal amino acid was expressed from the vector pET12a which supplies a signal sequence for export to the periplasm.

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.