Anomalous function of vimentin in chronic lymphocytic leukemia lymphocytes.

Chronic lymphocytic leukemia (CLL) lymphocytes manifest anomalous motility and cap formation. Since these processes involve cytoskeletal proteins, vimentin from intermediate filaments of normal and CLL lymphocytes was investigated using hetero- and monoclonal antisera. The antisera reacted predominantly with a 60-kD polypeptide, following sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of total lymphocyte proteins. When lymphocytes were stained by indirect immunofluorescence, normal lymphocytes demonstrated well defined cytoplasmic fibrils that capped spontaneously after contact with a glass surface and incubation at 37 degrees C. This capping was dependent on energy and intact microfilaments. Lymphocytes from patients with CLL showed several patterns. In one group, the initial staining was weak, and few capped cells were present after incubation. Lymphocytes from other patients had either normal or aberrantly organized fibrils in which capping was diminished. In another group, a fibrillar pattern with normal or increased capping was seen. In total, 47% +/- 5.1% (mean +/- SE) of normal lymphocytes capped after a 1-hr incubation at 37 degrees C (n = 12) compared to 21% +/- 5.1% for CLL lymphocytes (n = 20, p less than 0.002). Purified subpopulations of normal B and T cells did not differ from unfractionated normal lymphocyte populations. These results demonstrate an anomalous vimentin capping response in CLL lymphocytes. They also show that the arrangement of vimentin in these cells differs from that of normal lymphocytes.

IgM myeloma, a distinct entity in the spectrum of B-cell neoplasia.

The distinction between multiple myeloma and Waldenström's macroglobulinemia can usually be made on the basis of clinical, histologic, and immunologic findings. However, some patients have features of both diseases. Two patients who had IgM monoclonal gammopathies and plasma cell neoplasia are presented. Both had bone lesions, monoclonal IgMk, and bone marrow infiltration with plasma cells. The presence of plasma cells was verified by electron microscopy. Immunoperoxidase studies in both cases showed positive staining with mu and kappa antisera only, suggesting that these plasma cells were the source of the IgMk protein. Using the criteria of monoclonal IgM, plasma cell neoplasia, and bone lesions, 28 similar cases were found. The analysis of clinical data revealed an increased incidence of lytic bone lesions, decreased IgG and IgA, renal failure, hypercalcemia, and Bence-Jones proteinuria, as are commonly seen in multiple myeloma. It also demonstrated an increased incidence of hyperviscosity symptoms, lymphadenopathy, hepatosplenomegaly, and mucous membrane bleeding, as are often seen in Waldenström's macroglobulinemia. Other common findings were anemia and plasma cell leukemia. These data suggest that, although rare, IgM myeloma should be considered a distinct clinical entity in the spectrum of B-cell malignancies with characteristics of both multiple myeloma and Waldenström's macroglobulinemia.

Acylation of alpha-chymotrypsin by oxygen and sulfur esters of specific substrates: kinetic evidence for a tetrahedral intermediate.

The acylation step of the alpha-chymotrypsincatalyzed hydrolysis of N-acetyl-L (or DL)-tryptophan p-nitrophenyl, p-nitrothiophenyl, ethyl, and thiolethyl esters has been studied by the stopped-flow technique at 25 degrees . The acylation rate constant, k(2), and the enzyme substrate dissociation constant, K(s), were directly determined at pH 4, 5, and 8. Steady-state kinetics were studied at pH 7. The k(2) values are nearly identical for oxygen esters and their sulfur counterparts, whereas the K(s) value of the ethyl ester is larger by an order of magnitude than those of the other three. The results strongly suggest that oxygen and thiol esters of these specific substrates are hydrolyzed via the same pathway, and furthermore that acylation consists of more than one step, the formation and breakdown of a tetrahedral intermediate, the former being rate-determining. Effects of leaving-group hydrophobicity on k(2) and K(s) are also discussed.