1365 this defect has not been previously clearly apparent. The Km of the cells, with respect plasma-membrane enzyme inInnormal whole-cell homogenates, to N.A.D.H., is 1.7 mol/1. when assays are undertaken with high concentrations of N.A.D.H., the properties and activity of the plasma-membrane enzyme have been masked by N.A.D.H. oxidation by other cell components. Thus total N.A.D.H. oxidation in C.G.D. cells was found to be only partially reduced by Baehner and Karnovskylg and to be normal by Holmes Grey and Good,19 all of whom used N.A.D.H. at a concentration of 2.5mmol/l. The presence of a functionally imperfect enzyme correctly situated in the plasma membrane, which may be the case in the young man with C.G.D. in this study, could explain the observation that, although the reduction ofN.B.T. within phagocytic vacuoles of all patients with C.G.D. is abnormally slow, it can be demonstrated after variable delay in some individuals.6 It is likely that the observed variation in the severity of the disease process6 20 depends on the extent to which the function of the enzyme is compromised, possibly by a whole spectrum of distinct defects, in each individual patient. The elucidation of this enzyme defect clarifies the cell biology associated with phagocytosis. The cidal enzyme is thus an N.A.D.H. dehydrogenase which produces superoxide16 and is activated during phagocytosis, possibly when the invaginated plasma membrane is exposed to N.A.D.H. in the cytosol. Oxidation of the "free radical scavengers" ascorbic acid and glutathione2l by hydrogen peroxide, superoxide, and other radicals diffusing out of the phagocytic vacuole into the surrounding cytosol results in a secondary enhanced consumption of and consequent stimulation of the N.A.D.P.H. hexose monophosphate shunt. 16 22 The

reason

why

characterised is

now

We thank Dr D. Webster, Dr J. M. Goldman, and Prof. J. Soothill for allowing us to study patients under their care. T. J. P. received financial support from the Wellcome Trust.

REFERENCES 1. Berendes, H., Bridges, R. A., Good, R. A. Minn. Med. 1957, 40, 309. 2. Janeway, C. A., Craig, J., Davidson, M., Downey, W., Gitlin, D., Sullivan, J. C. Am. J. Dis. Child. 1954, 88, 388. 3. Quie, P. G., White, J. G., Holmes, B., Good, R. A. J. clin. Invest. 1967, 46, 668. 4. Klebanoff, S. J. A. Rev. Med. 1971, 22, 39. 5. Baehner, R. L., Nathan, D. G. New Engl. J. Med. 1968, 278, 971. 6. Nathan, D. G., Baehner, R. L., Weaver, D. K. J. clin. Invest. 1969, 48, 1895. 7. Segal, A. W. Lancet, 1974, ii, 1248. 8. Baehner, R. L., Nathan, D. G. Science, 1967, 155, 835. 9. Hohn, D. C., Lehrer, R. I. J. clin. Invest. 1975, 55, 707. 10. Curnutte, J. T., Kipnes, R. S., Babior, B. M. New Engl. J. Med. 1975, 293, 628. 11. Holmes, B., Park, B. H., Malawista, S. E., Quie, P. G., Nelson, D. L., Good, R. A. ibid. 1970, 283, 217. 12. Gray, G. R., Klebanoff, S. J., Stamatoyannopoulos, G., Austin, T., Naiman, S. C., Yoshida, A., Kliman, M. R., Robinson, G. C. F. Lancet, 1973, ii, 530. 13. Gold, S. B., Hanes, D. M., Stites, D. P., Fudenberg, H. H. New Engl. J. Med. 1974, 291, 332. 14. Gifford, R. H., Malawista, S. E. J. Lab. clin. Med. 1970, 75, 511. 15. Segal, A. W., Peters, T. J. Clin. Sci molec. Med. 1975, 49, 591. 16. Segal, A. W., Peters, T. J. Unpublished. 17. Kane, S. P., Peters, T. J. Clin. Sci. molec. Med. 1975, 49, 171. 18. Baehner, R. L., Karnovsky, M. L. Science, 1968, 162, 1277. 19. Holmes Grey, B., Good, R. A. in Immunobiology (edited by R. A. Good, and D. W. Fisher); p. 55. Sunderland, Massachusetts, 1971. 20. Thompson, E. N., Soothill, J. F. Archs Dis. Childh. 1970, 45, 24. 21. Reed, P. W. J. biol. Chem. 1969, 244, 2459. 22. Wilkinson, R. W., Powars, D. R., Hochstein, P. Biochem. Med. 1975, 13, 83. 23. Amar-Costesec, A., Wibo, M., Thinès-Sempoux, D., Beaufay, H., Berthet, J. J. Cell Biol. 1974, 62, 717.

THE ABSENCE OF B-CELL ANTIGEN B2 FROM LEUKÆMIA CELLS AND LYMPHOBLASTOID CELL LINES

RONALD J. BILLING RONALD HONIG

PAUL I. TERASAKI PATRICIA PETERSON

Department of Surgery, School of Medicine, University of California, Los Angeles, California 90024, U.S.A. 60 leukæmia patients with acute mylogenous leukæmia, chronic myelocytic leukæmia, acute lymphatic leukæmia, and chronic lymphocytic leukæmia were tested for five specificities of the new B-lymphocyte alloantigenic system. Two specificities of the first B-cell locus were significantly lower in frequency than in B lymphocytes from 105 controls. B-cell group 1 was found in 18% of leukæmia patients vs. 48% of controls (P

The absence of B-cell antigen B2 from leukaemia cells and lymphoblastoid cell lines.

1365 this defect has not been previously clearly apparent. The Km of the cells, with respect plasma-membrane enzyme inInnormal whole-cell homogenates,...
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