Immunobiological features of the galactoside lectin L-Lc isolated from the Argentine mistletoe Ligaria cuneifolia.

Ligaria cuneifolia has been used in Argentine folk medicine and is currently employed as substitute for the European mistletoe (Viscum album) as hypotensor agent. Extracts from V. album are widely used in cancer therapy and the antineoplasic effect is attributed to their cytostatic/cytotoxic and immunomodulatory actions. When studying immunomodulatory effects of L. cuneifolia extracts (Lc extracts), they inhibited proliferation of murine mitogen-activated lymphocytes, leukaemic lymphocytes (LB) and breast tumour cells (MMT). The aim of this work was to isolate and identify lectins from Lc extracts and investigate their immunobiological actions. A galactoside lectin (L-Lc) of 57 kDa was isolated. A polyclonal antiserum obtained against Lc extract recognised both L-Lc and MLI (V. album lectin), suggesting the possibility of shared epitopes. Treatment of LB tumour cells with L-Lc (0.01 and 0.1 microg/ml) produced up to 40.0+/-6.9% inhibition of cell growth, which seems partly mediated by apoptosis (apoptosis of L-Lc treated cells 58.4+/-10.3% versus non-treated cells 38.1+/-8.8%; P<0.05), analysed by acridine orange and ethidium bromide staining. Inhibitory effect on ConA stimulated splenocyte growth was non-significant, while a mitogenic effect was observed on normal murine splenocytes and MMT cells. L-Lc in non-cytotoxic concentrations (250 ng/ml) modified mRNA expression of IL-10 but neither that of TGF-beta nor of IL-2 produced by LB cells. In addition, 43.9+/-0.5% reduction in NO production by LPS-stimulated murine macrophages was found. Finally, survival rates of LB tumour-bearing mice treated or not with Lc extract or L-Lc failed to show significant differences.

[Differential binding of hyaluronic acid in 2 CD44+ sublines. Relationship with tumor infiltration]. / Unión diferencial de ácido hialurónico en dos sublíneas celulares CD44+. Posible implicancia en la infiltración tumoral.

We have established and characterized a cell line (LBL) from a spontaneous murine T lymphoma LB. Histopathological analysis has demonstrated LB primary tumor infiltration in spleen, lymph nodes, liver, thymus, bone marrow and lung. However LBL cells infiltrated all these organs except lung. Two sublines with different growth behavior were derived from LBL cell line. One of them grew in suspension as clusters (LBLc) while the other one grew as adherent monolayers (LBLa). Growth rate, response to mitogenic stimuli and apoptosis induction were different among the parental cell line and the derived sublines. CD44 was expressed constitutively in LBL and LBLa cells. In contrast LBLc cells only expressed similar levels of this molecule when stimulated with PMA. LBLa cells showed hyaluronic acid (HA) binding properties, while LBL and LBLc cells were not able to bind HA even when activated with PMA. We postulate that differences in HA binding could be related with different infiltration behaviors.

Unión diferencial de ácido hialurónico en dos sublíneas celulares CD44+. Posible implicancia en la infiltración tumoral. / [Differential binding of hyaluronic acid in 2 CD44+ sublines. Relationship with tumor infiltration]

We have established and characterized a cell line (LBL) from a spontaneous murine T lymphoma LB. Histopathological analysis has demonstrated LB primary tumor infiltration in spleen, lymph nodes, liver, thymus, bone marrow and lung. However LBL cells infiltrated all these organs except lung. Two sublines with different growth behavior were derived from LBL cell line. One of them grew in suspension as clusters (LBLc) while the other one grew as adherent monolayers (LBLa). Growth rate, response to mitogenic stimuli and apoptosis induction were different among the parental cell line and the derived sublines. CD44 was expressed constitutively in LBL and LBLa cells. In contrast LBLc cells only expressed similar levels of this molecule when stimulated with PMA. LBLa cells showed hyaluronic acid (HA) binding properties, while LBL and LBLc cells were not able to bind HA even when activated with PMA. We postulate that differences in HA binding could be related with different infiltration behaviors.