Products of psoralen photooxidation possess immunomodulative and antileukemic effects.

It has been proposed that the therapeutic effect of PUVA (psoralens+UVA radiation) is connected to its immunomodulative properties, and that the molecular basis of such properties is the oxygen-independent photoaddition of psoralens to DNA. We have investigated effects of preliminary photooxidized psoralens (POP) on the delayed-type hypersensitivity reaction (DTH) to sheep red blood cells and on growth of grafted T-cell lymphoma EL-4 in mice. We have shown that intravenous injection of POP at low concentrations activated, and at high concentrations suppressed, DTH.

Immunological tolerance to xenogeneic grafts induced by cyclophosphamide in adult animals.

Data on tolerance of mice to rat tissue grafts obtained during the last 20 years are presented in this article. The method of tolerance induction, which spared recipients' lymphoid tissue and which needed no supporting antigen or immunodepressant injection, is described. These tolerant mice had long-lasting (more than 6 months) xenograft survival, had no cytotoxic antibodies and delayed-type hypersensitivity (DTH) reaction to donor antigens but showed only a partial decrease in the levels of mixed lymphocyte reaction (MLR) and non-cytotoxic antibody production.

Autoimmune response induction and regulation in rat erythrocyte-immunized mice.

The process of antibody formation to self-red blood cells (RBC) has been studied in rat RBC (rRBC)-immunized mice. A positive correlation was noted between antibody production to mouse RBC (mRBC) and rRBC in some mouse strains. The low responsiveness on both indices was overcome by s.

Delayed-type hypersensitivity to transplantation antigens in mice and its investigation under conditions of allograft and xenograft tolerance.

Methods of induction of delayed-type hypersensitivity (DTH) to transplantation alloantigens and xenoantigens in mice were developed. They include the s.c.

Immunological status of mice with long-standing allogeneic or xenogeneic neonatal heart grafts.

Adult mice were thymectomized and given 1 X 10(8) allogeneic or xenogeneic spleen cells i.v. On the day following cell injection, the mice were treated with 200 mg/kg cyclophosphamide (Cy) i.

Macromolecular antitumor agents from Chamaenerium angustifolium.

The antineoplastic substances isolated from Chamaenerium angustifolium, Chanerol, a macromolecular polyphenol, and its complex with polysaccharide, Chanerozan, have been studied in vitro in tests of haemagglutination, tumor cell agglutination, leucoagglutination and some others. The results obtained show Chanerol as a new phytohaemagglutinin (lectin) which has no group specificity for human erythrocytes (ABO system). As distinct from other lectins (proteins) Chanerol belongs to another chemical class (macromolecular polyphenols) and has no effect on lymphocytes in leukoagglutination and blast transformation tests.