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Antibodies to the factor HLDF are shown to be specific markers of apoptosis and permit the estimation of the rate of programmed cell death in the course of a normal menstrual cycle and in pathologic endometrial processes. HLDF expression in the epitheliocytic cytoplasm makes it possible to evaluate apoptosis at early stages, before the emergence of the first morphological signs and after apoptotic body formation. The study shows increased apoptotic processes at the end of a normal menstrual cycle and during neoplastic cell transformation. Antibodies to the HLDF factor may be used as a new immunohistochemical marker for the differential diagnosis of benign and malignant endometrial processes.

It was shown that the full-size neurotrophic factor from pigment epithelium (PEDF) induces the cell differentiation of the human promyelocyte leukemia cell line HL-60. A structural analysis of PEDF revealed in its C-terminal region a six-membered peptide fragment PEDF-(352-357) (PEDF-6) whose sequence is highly homologous to the 41-46 fragment of the active site of the human leukocyte differentiation factor HLDF (HLDF-6). The biological effect of PEDF and synthetic peptides PEDF-6 and HLDF-6 on the HL-60 cells and the early gastrula ectoderm of Xenopus laevis embryos was studied. On the basis of the structural and functional homologies of HLDF, PEDF, and their homologous peptides and the computer models of the spatial structures of the full-size PEDF and the PEDF with the C-terminal fragment split off tby the cleavage of the Leu380-Thr381 bond in the serpin loop, a hypothesis on the functional role of the serpin loop in PEDF was put forward.

Six-membered peptide fragment TGENHR (HLDF-6) was identified in the HL-60 cell culture of human promyelocyte leukemia treated with retinoic acid when studying the differentiation factor HLDF of this cell line. HLDF-6 retains the ability of the full-size factor to induce the differentiation and arrest the proliferation of the starting HL-60 cells. It was shown that the synthetic peptide HLDF-6 has no specific receptors on the surface of the HL-60 cells but can affect the binding of interleukin IL-1 beta, a cytokine involved in proliferation, to the cell surface. It was found on a model of transplantable NSO myeloma that HLDF-6 has an antitumor activity.

A structural homology between the endogenous differentiation factor of the HL-60 cell line of promyelocyte leukemia (HLDF) and several DNA/RNA-binding and DNA/RNA-hydrolyzing proteins was revealed, and expression of the hldf gene in prokaryotic systems was studied. On the basis of these experiments, the amino acid sequence of an 8-membered fragment of HLDF with potential nuclease activity was identified. The synthetic octapeptide RRWHRLKE was shown to be capable of the cleavage of RNA, linear DNA from phage lambda, and all forms of plasmid DNA. We established that treatment of the HL-60 cell culture with this peptide (10(-6) M) results in an increase in the number of apoptotic cells and suggested that HLDF is involved in processes of apoptosis.

The effects of L-glutamic acid on the differentiation of HL-60 and K-562 cell lines and on the expression level of mRNAs encoding IL-1 beta, IL-6, and TNF alpha were studied. It was shown that TNF alpha actively induces the differentiation of these cell lines, whereas L-glutamic acid enhances its effect. Our results indicated that L-glutamic acid modulates the physiological state of the myeloid cell line in blood, in particular, by affecting both the reception and expression of cytokines functionally important for these cells.

L-Glutamic acid at a concentration of 0.1 microM was found to induce differentiation of the cell line of HL-60 promyelocytic leukemia into granulocytes or neutrophils. The HL-60 cells have no specific glutamate-binding sites, but L-glutamic acid influences the reception of several cytokines by these cells. At a concentration of 0.1 microM, L-glutamic acid completely inhibits the high-affinity binding of 125I-labeled human recombinant interleukin-1 beta (Kd = 0.32 nM) to the HL-60 cells, but does not affect their low-affinity binding (Kd = 13.3 nM) and does not change the total number of the IL-1 beta-binding sites. Preincubation of the HL-60 cells with 0.1 microM of L-glutamic acid increases 2.5 times the number of receptors for 125I-labeled human recombinant tumor necrosis factor beta. These results suggest that L-glutamic acid plays an important role in the differentiation of the blood myeloid cells.

Several retinoids with modified polar group were synthesized. Biological screening using HL-60 promyelocyte leukemia cells showed that the free carboxyl in the retinoid molecules is not the only group responsible for exhibiting the differentiating activity.

A new 8.2-kDa protein factor was isolated from cell culture of a promyelocyte leukemic HL-60 cell line that exhibited a differentiation-inducing effect upon the initial cell line. The primary structure of this factor was determined by sequencing the protein (N-terminal region) and the corresponding cDNA. A molecule of the differentiation factor secreted by HL-60 cells consisted of 54 amino acid residues and was glycosylated.

The catalytic component of calmodulin-independent adenylate cyclase of cattle cerebral cortex was solubilized and purified to the homogeneous state. The conditions for preparative obtaining of the enzyme on the column with immobilized antibodies to adenylate cyclase were found. These antibodies were proved to interact with the calmodulin-independent rather than the calmodulin-dependent form of the enzyme. Molecular mass of the calmodulin-independent adenylate cyclase determined electrophoretically is 140 +/- 10 kDa. Amino acid composition of the enzyme and sequences of its fragments (in total 300 amino acid residues) obtained upon treatment with lysyl-specific proteinase from Achromobacter liticus were determined. Clone containing a cDNA 605 bp insertion coding for the 183 amino acid residue fragment of adenylate cyclase was isolated from the bovine brain cDNA library. Homology of this fragment to the known sequences of Escherichia coli and Bordetella pertussis adenylate cyclases was revealed.