Differential scanning calorimetry was performed on the five major lens crystallin fractions [HM-alpha, alpha, beta H, beta L, and (beta s + gamma)] of the bovine lens as well as on more purified forms of alpha- and gamma-crystallins. All were found to be relatively thermally stable although the alpha-crystallin were found to at least partially unfold at an approximately 10 degrees C lower temperature than the beta and gamma fractions. Increasing protein concentration had little effect on gamma-crystallin thermograms but had marked effects on those of the alpha- and beta-crystallins. Increases in the thermal stability with increasing protein concentration for the beta-crystallins can be explained most simply by the known beta L/beta H equilibrium, but, in the case of the alpha-crystallins, excluded volume effects may be an important factor. In both cases, the increased stability at high concentrations could be of physiological relevance. As well as the expected endothermic unfolding transitions, all of the lens crystallins revealed exothermic peaks that correlate with protein precipitation. Interestingly, this phenomenon occurs only after extensive structural alteration in the case of the alpha-crystallins but is present very early in the initial stages of structural perturbation of the beta- and gamma-crystallins.

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Inhibition of the cryoprecipitation of cryoimmunoglobulins by neutral salts suggests that intermolecular electrostatic (charge-charge) interactions are responsible for their abnormal solution properties. To test this hypothesis, H+ titration curves and isoelectric points were measured for two monoclonal IgG cryoglobulins (Ger and Muk) and compared with four normal (cold soluble) monoclonal IgG. The cryoglobulin Ger manifested values outside the range encountered for the other proteins. The partitioning of the IgG proteins was also examined in aqueous polyethylene glycol-dextran two-phase systems in the presence of both positive and negative salt-induced electrostatic potentials across the phase interface. Both cryoglobulins were found to behave as if they were more negatively charged than the noncryoglobulins. The experiments support the hypothesis that the differences in solubility behavior of monoclonal cryoglobulin and noncryoglobulin proteins are caused by differences in the electrostatic properties of the proteins.

It was the aim of this study to investigate the antileukemic activities of recombinant interferon beta (rIFN beta) in chronic-phase CML in vitro and in vivo. Nine patients in the early chronic-phase of CML were treated in a phase-II trial with escalating doses of rIFN beta. In parallel, antiproliferative and immunomodulatory activities of rIFN beta and rIFN alpha 2b were studied in vitro. rIFN beta exhibited a significantly higher antiproliferative activity on hematopoietic progenitor cells of CML patients in vitro than rIFN alpha 2b. In contrast, only very limited clinical antileukemic efficacy of rIFN beta was observed. None of the patients achieved a complete or partial hematologic response (0% response rate, 0-36% 95 C.I.). Primary resistance of CML patients to rIFN beta treatment was caused neither by antibody formation against the recombinant material nor by deficient IFN receptor targeting and/or signaling; Induction of serum levels of beta-2-microglobulin (beta-2-m) and neopterin after administration of rIFN beta was comparable to that seen after administration of rIFN alpha. However, rIFN beta treatment less effectively induced biosynthesis of interleukin-1 receptor antagonist protein (IL-1-Ra) than rIFN alpha 2b. Thus, we conclude that rIFN beta at doses up to 12 MU/day s.c. is ineffective for treatment of chronic-phase CML. Further investigations into divergent biologic responses to various type-I interferons might help to elucidate mechanisms crucial for IFN action in patients with CML.