MODULATING ACTIVITY OF MISTLETOE LECTIN-1 AND LECTIN-2 ON THE LYMPHATIC-SYSTEM IN BALB C-MICE/

The galactoside-specific lectin (mistletoe lectin-l, VAA-1) and the N- acetylgalactosamine-specific lectin (mistletoe lectin-2, VAA-2) were p urified from aqueous mistletoe extract and checked for their immunoact ive potency. Regular subcutaneous administration of the optimal immuno modulating VAA-1/VAA-2 dosage (1 ng lectin/kg body weight) could be sh own to modulate thymocyte proliferation, maturation, emigration and ac tivation in BALB/c-mice. Thus, the increase in thymocyte counts was st atistically significant after VAA-2 treatment. However, analogue VAA-2 applications significantly decreased thymocyte proliferation. Determi nations of lymphatic subsets revealed considerable upregulation (after VAA-1 treatment) and significant downregulation (after VAA-2, treatme nt) of immature L 3 T 4(+)/Lyt-2(+) thymic cells. Counts of mature cel ls expressing helper/inducer (L 3 T 4(+)) or suppressor/cytotoxic (Lyt -2(+)) phenotypes did not present remarkable differences after VAA-1/V AA-2 administration. Counts of BALB/c-mouse peripheral blood cells rev ealed evident (statistically non-significant) increases of lymphocytes (PBL) and monocytes (PBM) after VAA-1 treatment, however, cell counts after VAA-2 administration were comparable ro non-treated control ani mals. The determination of activated PBL expressing interleukin IL-2 r eceptors proved that VAA-1 induced a potent immunostimulation, since t hese cells were significantly enhanced after VAA-1 administration but not after VAA-2 treatment.