Effects of an antitumor multipeptide complex on immunocompetent and antigen-responsive cells.

The investigations, performed to study the possible mechanism of action of PTC, of its single constituents and of meta-levo-sarcolysin (m-L-SL) on the human immunocompetent system, are reported. The study entailed the evaluation of the effect of PTC, of its peptides and of m-L-SL on the various lymphocyte classes, employing all the more sophisticated immunological techniques such as: a) lymphocyte cultures stimulated with the various mitogens, (T and B lymphocytes); b) E rosettes (T lymphocytes); c) EA rosettes (lymphocytes with Fc receptors for IgG); d) EAC rosettes (lymphocytes with the C3 receptors); e) autoradiography and intracytoplasmic immunofluorescence (in vitro immunoglobulin neosynthesis); f) CdL (Complement-dependent Lymphocytotoxicity); g) LALI (Lymphocyte Antibody Lymphocytolytic Interaction); h) CML (antibody independent cytotoxicity i.e. Cell-Mediated Lympholysis). The evidence points out that the PTC effect on T and B lymphocytes is not comparable to that of m-L-SL which does not discriminate between the two lymphocyte populations while PTC, besides showing a scarce immunodepressive effect, preferentially affects B lymphocytes rather than T lymphocytes as shown also by the E rosette pattern. Significantly different appears also the influence of PTC, as compared with that of m-L-SL on the lymphocytes with Fc receptors for IgG (EA rosettes) and with receptors for the third component of complement (EAC rosettes) as well as on the cytotoxicity test and on the antibody dependent (LALI) and complement dependent (CdL) lytic effect. The data gleaned from this investigation allow evaluating both the effects of PTC on the immunocompetent system and the difference of its action from that of m-L-SL.