Granulocyte function in malignant monoclonal gammopathy

Infections in patients with leukemia and lymphoma

Infectious complications remain a significant issue in the care of patients with hematologic malignancies. Inherent immune defects related to the primary disease process are present in patients with disorders such as chronic lymphocytic leukemia, multiple myeloma, hairy cell leukemia, and Hodgkin lymphoma. Therapy-related immunosuppression is also commonplace in these patients. This includes not only treatment-related neutropenia, but also defects in cell-mediated immunity, such as those that occur with purine analog therapy. In this chapter, we will review the pathogenesis of infection in these disorders, as well as the spectrum of infectious complications seen and suggested strategies for the prevention of infection.

The effect of ranitidine on cellular immunity in patients with multiple myeloma

Multiple myeloma is characterized by an increased susceptibility to infections and to other malignancies. In a double-blind, placebo-controlled study the potential impact of immunomodulation by ranitidine was studied in 20 patients with multiple myeloma. Three patients were untreated, while 17 after previous cytotoxic therapy were in a stable phase of their disease. All were without clinical signs of infections and at that time had not been treated with other immunomodulating agents. The patients were randomized to oral ranitidine 300 mg twice a day for 21 days or placebo, and several immunological parameters related to multiple myeloma were studied. The blood monocyte chemotactic response was improved in patients treated with ranitidine, and superoxide anion production increased from 2.02 nmol/min to 3.86 nmol/min (median values), while it was unchanged in patients given placebo (2.19-2.25 nmol/min) (P less than 0.005 between groups). Among ranitidine-treated patients spontaneous NK cell activity was unchanged, while in vitro interleukin-2- and interferon-alpha-stimulated NK cell activity decreased (P less than 0.03, respectively). As production of oxygen radicals constitutes an important mechanism of monocyte killing activity against microorganisms and probably against malignant cells, it is suggested that ranitidine may be of beneficial impact in the treatment of multiple myeloma.

Complement abnormalities in multiple myeloma

PURPOSE

Patients with multiple myeloma have been shown to have defective opsonization and C3 deposition. Previous studies have suggested that defective C3 deposition may be related to a failure of C3 activation in myeloma serum, the mechanism of which is unknown. We therefore decided to investigate the underlying mechanism responsible for the failure in C3 activation and deposition.

PATIENTS AND METHODS

The study consisted of 10 patients from whom a total of 12 serum specimens were obtained. Normal serum was prepared from a pool of serum specimens in four healthy male donors. We evaluated, in vitro, the kinetics of C3 deposition onto zymosan using radiolabeled C3 under various conditions. We also measured the serum levels of a variety of complement components using standard methods.

RESULTS

Five of 10 patients' sera demonstrated poor C3 deposition onto zymosan at all time points, whereas an additional two showed poor C3 deposition at early time points but a rebound to normal by 30 minutes. Multiple components of the classical and alternative complement pathways were decreased in many patients, with the most striking abnormalities occurring in those with the poorest C3 deposition. No single complement component abnormality was found to be common to the group. Elevations in Bb fragment concentration strongly suggest in vivo activation as the likely mechanism for depletion of alternative pathway components; the mechanism for classical pathway abnormalities is less clear. There was an inverse correlation between paraprotein concentration and abnormal C3 deposition (p less than 0.0001) and C3 (p less than 0.0005) and C4 (p less than 0.0001) concentrations. However, no consistent evidence of fluid-phase complement consumption was present.

CONCLUSION

The defect in C3 activation and deposition in multiple myeloma cannot be explained on the basis of a single complement component abnormality but rather is due to a heterogeneous group of complement abnormalities. Although no correlation between in vitro abnormalities and clinical status was identified in this small group of patients, it is likely that the described complement defects play an important role in defective host defense in multiple myeloma.

Decrease of Fc gamma and C3b receptor-bearing granulocytes and of T lymphocytes in myelomatosis

18 patients with myelomatosis had lower percentages of granulocytes bearing receptors for Fc gamma (47.6%) and C3b (43.0%) than controls (80.4% and 75.0%). The percentage of T lymphocytes was decreased in patients when untreated sheep erythrocytes were used as indicator cells. Patients with high serum IgG levels had lower percentages of T lymphocytes. There was no significant difference in receptor profile between treated and untreated patients. The decrease in Fc gamma and C3b receptor-bearing granulocytes in myelomatosis is probably not due to serum or plasma factors since (a) the distribution of receptor-bearing lymphocytes was not different from that of the controls; (b) extra washings of cells or overnight incubation did not enhance the percentage of receptor positive cells; and (c) incubation of normal granulocytes in sera or plasma from myelomatosis patients did not cause a more pronounced reduction in the proportions of Fc gamma of C3b receptor-bearing cells than incubation in normal sera or plasma.

Mechanisms of decreased leucocyte adhesiveness and migration in plasma from patients with IgG myelomatosis

The adhesiveness of leucocytes in human plasma was decreased by the addition of IgG M-protein, commercial IgG, F(ab)2-fragments, or bovine serum albumin (BSA). Leucocyte migration was inhibited by IgG M-protein and commercial IgG, but not by reduced and alkylated IgG, F(ab)2-fragments or BSA. Guinea pig serum (GPS) strongly enhanced leucocyte migration in Hanks' balanced salt solution. This effect was abolished by hydrazine treatment or heating, and reduced, but not abolished, by zymosan treatment. C4-deficient guinea pig serum (C4-def-GPS), but not zymosan treated C4-def-GPS stimulated migration. In IgG myeloma sera migration was enhanced by the addition of C4-def-GPS and by untreated or heated, but not hydrazine treated GPS, and inhibited by zymosan treated GPS. IgG M-protein inhibits leucocyte adhesiveness and migration. Migration is specifically inhibited by the intact IgG, probably through complement activation with consumption of heat stable chemokinetic factor(s) and production of migration inhibitors.