Mantle cell lymphoma salvage regimen: synergy between a reprogrammed oncolytic virus and two chemotherapeutics.

Measles virus (MV)-PNP H(blind)antiCD20 is a CD20-targeted and prodrug convertase-armed MV that temporarily controls growth of lymphoma xenografts in severe combined immunodeficiency (SCID) mice in combination with fludarabine phosphate (fludarabine). Herein, we examine the replication of this targeted virus and of a vaccine-lineage MV in disease bulks and circulating cells from mantle cell lymphoma (MCL) patients, and show that only the targeted virus is specific for CD20-expressing cells. We then assessed the efficacy of different regimens of administration of this virus in combination with fludarabine and cyclophosphamide (CPA) in an MCL xenograft model. We show that CPA administration before the beginning of virus treatment enhances oncolytic efficacy, likely through temporary immunosuppression. An interval of 1 week between intravenous virus administration and fludarabine treatment further enhanced oncolysis, by synchronizing maximum prodrug convertase expression with fludarabine availability. Finally, three 23-day courses of triple sequential treatment with CPA, virus and fludarabine treatment resulted in complete regression of the xenografts. Secondary disease symptoms interfered with survival, but average survival times increased from 22 to 77 days. These studies document a reprogrammed oncolytic virus, consolidating the effects of two chemotherapeutics, a concept well suited for a phase I clinical trial for MCL patients for whom conventional therapies have failed.

Modulation of platelet aggregation by native DNA - initial description of platelet receptor type, number and discrimination for native DNA.

Native DNA (dsDNA) induces the aggregation of isolated human platelets. Using isotopically labeled dsDNA (125I-dsDNA) and Scatchard analysis, a single class of platelet receptor was detected with a KD = 190 pM and numbering approximately 275/platelet. This receptor was discriminatory in that heat denatured dsDNA, poly A, poly C, poly C x I and poly C x poly I failed to substantially inhibit either the platelet binding of, or platelet aggregation induced by, dsDNA; by themselves, these polynucleotides were ineffective as platelet agonists. However, poly G, poly I and poly G x I effectively and competitively inhibited platelet binding of the radioligand, independently activated the platelet and when used at a sub-activating concentration decreased the extent of dsDNA stimulated platelet aggregation. These data depict a receptor on human platelets for dsDNA and perhaps certain additional polynucleotides and relate receptor-ligand interactions to a physiologic platelet function.

Circadian rhythms of plasma corticosterone binding activity in the rat and the mouse.

Corticosterone binding activity (CBA) and corticosteroids were measured by competitive protein binding techniques in plasma samples drawn from rats and mice at different times of day. Circacian rhythms of plasma CBA were found in both rats (onset of 14-h daily photoperiod: 0600) and mice (onset of 14-h daily photoperiod: 0700). The plasma CBA rhythm was bimodal in rats with peaks at 1000 and 1800 and unimodal in mice with peak level from 0100 to 0500. Circadian rhythms of plasma corticosteroid concentration with peaks during the late afternoon were confirmed in both rats and mice. The plasma CBA rhythms appear to be related to the circadian rhythms of both locomotor activity and plasma corticosteroid concentration.

Platelet inhibitory effects of CRP preparations are due to a co-isolating low molecular weight factor.

We previously reported that C-reactive protein (CRP), an acute phase reactant, inhibits platelet activation through an effect upon a factor(s) critical to ADP-mediated secondary wave platelet aggregation but independent of a direct effect upon platelet contractile elements. However, a role for an accessory factor in this inhibitory effect became of concern because of an inconsistency in the effects of CRP preparations upon the platelet: inhibition was lost upon storage and CRP preparations differed, on a weight basis, in inhibitory capacity and sensitivity to the presence of the CRP ligand C-polysaccharide (CPS(. The studies presented herein were thus intended to assess whether an accessory factor was involved in the inhibition of platelet activation observed with CRP. We report that the activity of the inhibitory CRP preparations resulted from association with a low molecular weight factor (LMF) with an apparent nominal molecular weight of 8300-12,500 and an A280:A260 ratio of approximately 0.4. Purified CRP did not inhibit platelet responsiveness but CRP with associated LMF (CRP-LMF) did. Moreover, the inhibitory capacity of CRP-LMF but not LMF was substantially reversed in the presence of CPS. These studies indicate that the platelet inhibitory properties of CRP preparations result from and are contingent upon the presence of a co-isolating low molecular weight factor.

Chemiluminescence assay for detection of anti-platelet antibodies.

A chemiluminescence (CL) assay for detection of antiplatelet antibodies was developed. Platelets sensitized with a xenogeneic antiplatelet serum or a potent anti-Pla1 serum stimulated granulocytes to produce CL. Other antibodies detectable by 51chromium release and immunofluorescent assays were not discerned by the CL assays.