P. C. Vincent

The Mechanism of Neutropenia in Felty's Syndrome

Summary. Neutrophil kinetics were studied in 17 patients with Feltys syndrome using an in vitro diisopropylfluorophosphate‐32P technique. Excessive margination of neutrophils was present in all patients, and was solely responsible for the neutro‐penia in 12. Five patients had a total blood neutrophil pool which was so low that they would have been neutropenic even with a normal ratio of marginated to circulating cells; in these the production rate was subnormal. In no case was neutropenia due to shortened nueutrophil survival. There was no correlation between either the degree of marrow cellularity, or serum lysozyme levels, and the measured neutrophil production rate. Two patients studied before and after splenectomy showed improvement in kinetic abnormalities following operation. We conclude that the principal mechanism responsible for the neutropenia in Feltys syndronie is excessive margination of cells. In about one third of patients neutrophil production is subnormal in addition, but excessive neutrophil destruction is an uncommon finding. Conventional laboratory investigations are of little or no help in defining the mechanism in an individual patient. The value of splenectomy still has to be established, although short‐term improvement in kinetic parameters may occur.

Disseminated atypical mycobacterial infection in hairy cell leukemia

Summary The clinical features are described of disseminated atypical mycobacterial infection of the subcutaneous tissues occurring in a patient 3 yr after the diagnosis of hairy cell leukemia. Skin biopsy identified the causative organism as an atypical mycobacterium of the M. avium‐intracellulare‐scrofulaceum (MAIS)complex. In vitrostudies showed that the patient had impaired mononuclear cell phagocytosis. These findings lend support to the hypothesis of a specific defect of immunity in hairy cell leukemia.

CONTROL OF LYMPHOCYTE LEVEL IN THE BLOOD

Abstract This hypothesis proposes: (1) that small lymphocytes carry a recognition site on their surface; (2) that detection of lymphocytes carrying this recognition site (possibly during migration across the endothelium of the post-capillary venule) inhibits lymphocyte proliferation, thus maintaining normal numbers of lymphocytes; (3) that the recognition site is identical with the phytohaemagglutinin-responsive site and is closely associated with sites reacting with specific antigens; and (4) that the recognition site is lost or blocked in chronic lymphocytic leukaemia and in some of the lymphomas.

Inhibition of Normal Human Granulopoiesis in Vitro by Non‐B Non‐T Lymphocytes

Summary Normal non‐adherent mononuclear cells were shown to inhibit colony formation by normal human marrow cells cultured for 7 d in semi‐solid agar. Inhibition was the same using cells from the marrow donor or from an unrelated normal subject, and was shown to be dose‐dependent over the range of 4 × 105 to 6 × 103 mononuclear cells per 1 × 105 marrow cells plated. Inhibition was not seen in 14 d cultures, and it is postulated that colony‐forming cells sensitive to lymphocyte inhibition belonged to the population known to give rise to colonies after 7 d in culture. Cell fractionation studies showed that inhibition was due to non‐B non‐T lymphocytes, purified B cells or T cells being neither inhibitory nor stimulatory. Inhibition was only shown with intact viable lymphocytes and it was not possible to extract inhibitory activity from the cells, or to produce inhibition by media conditioned by lymphocytes. The effect was apparently due to a direct action on colony‐forming cells in the marrow and was not due to inhibition of colony stimulating activity (CSA) production, or to absorption or inactivation of CSA. These results emphasize the need to include appropriate controls when looking for possible cell‐mediated inhibitors in disease states, particularly when 7 d cultures are used.

INHIBITOR OF IN-VITRO GRANULOPOIESIS IN PLASMA OF PATIENTS WITH RENAL FAILURE

Plasmas from 31 patients with moderately severe to severe renal failure inhibited granulopoietic colony formation in human marrow in vitro. The inhibitory activity could not be removed by in-vitro dialysis but was present in an ultrafiltered fraction of molecular weight less than 25 000 daltons. It inhibited the production of colony-stimulating activity (C.S.A.) by leucocytes in the culture system but had little or no effect on preformed C.S.A. or on the granulopoietic colony-forming cell itself. The level of plasma inhibitory activity correlated with the degree of azotaemia but not with the neutrophil or monocyte counts. Despite the potency with which granulopoiesis was inhibited in vitro, none of the patients was severely neutropenic, and only 4 had mild neutropenia (neutrophil count 1.5--2.1 x 10(9)/1).

The measurement of granulocyte kinetics.

Studies using 3H-TdR, DF32P or 51Cr have all contributed important information concerning neutrophil kinetics in normal and abnormal conditions. Recent evidence, however, suggests that DF32P underestimates, and 51Cr overestimates, the blood neutrophil T1/2 and that both isotopes overestimate the TBNP, compared with 3H-TdR-derived data. The differences are quantitative and not qualitative, and the principles of blood neutrophil kinetics defined by DF32P studies are still valid. 3H-TdR studies are impractical for general use, and clinical measurement of neutrophil kinetics will have to continue to rely on the use of either DF32P or 51Cr. Comparison of abnormal findings with normal values obtained using the same isotope is probably valid for either technique. Changes in neutrophil kinetics leading to a neutrophil leucocytosis in different situations are fairly predictable from published data. In neutropenias, however, kinetic studies might be needed to delineate the relative contributions of under-production, shortened survival and excessive margination in the individual patient.

CFU-C inhibitors in aplastic anaemia

SummaryPeripheral blood lymphocytes from 15 patients with marrow aplasia were tested for their ability to inhibit the proliferation of normal granulopoietic precursor cells (CFU-C) in agar culture, relative to the inhibitory effect of normal lymphocytes studied in parallel. Eight of the 15 patients with marrow aplasia had lymphocytes which were significantly less inhibitory to normal CFU-C than controls whereas 3 patients had lymphocytes which were significantly more inhibitory. Two further patients who had recovered from marrow aplasia were also studied. The effect of patients plasma and normal plasma on normal CFU-C proliferation was also studied and in 1 case a potent inhibitor of granulopoiesis was demonstrated. In 9 cases CFU-C could be cultured from patients marrow, and parallel studies examining the effects of lymphocytes or plasma on patients CFU-C. In none of the 9 marrow samples tested was inhibition by patient lymphocytes significantly greater than normal controls.The results highlight the heterogeneity inherent in the study of aplastic states and serve to underline the importance of controls. In only a minority of cases (20%) was lymphocyte suppression of normal granulopoiesis by lymphocytes from patients with aplastic anaemia significantly greater than normal lymphocyte suppression.

Changing clinical, morphological and immunological patterns in chronic lymphocytic leukaemia

Summary Two cases of chronic lymphocytic leukaemia are presented in which, in the terminal phase of the disease, a population of abnormal lymphocytes similar to those seen in lymphosarcoma cell leukaemia replaced the morphologically normal small lymphocytes observed previously. Immunologically, this change coincided with a striking alteration in the pattern of surface immunoglobulin markers. In both cases, most cells initially carried IgM and in both cases these were replaced by cells carrying IgG as the number of abnormal lymphocytes increased. In addition, the use of anti‐5 antiserum in the second case revealed the coexistence of large numbers of IgD‐bearing lymphocytes as well. Calculations showed that more than half the cells present at that time must have been carrying both IgD and IgG surface markers.

Steroid Responsive Cyclical Neutropenia

SummaryA 19-year old girl with severe cyclical neutropenia associated with life-threatening infection and who responded dramatically to the administration of oral prednisolone is described. During reduction and eventual cessation of steroid therapy normal or near normal neutrophil counts have been maintained, and there has been parallel improvement in clinical well-being. Prior to therapy and at a time of peak blood neutrophil count low numbers of granulocyte-macrophage progenitor cells (CFU-C) were found in the patients bone marrow, and her lymphocytes co-cultured with normal marrow failed to show the inhibitory effect normally seen with normal lymphocytes.The findings in this patient are compared with those in the two other cases where cyclical neutropenia has been shown to respond to steroids.

Studies of muramidase in haematological disorders: serum and marrow muramidase in leukaemia

Summary Estimations of serum and marrow plasma muramidase were made in 39 adults with leukaemia. In the 33 patients studied prior to therapy, the absolute levels of marrow muramidase paralleled those of serum muramidase and reflected the type of leukaemia present. The normal marrow to serum muramidase ratio lies between 1.5 : 1 and 3 : 1 and in only 2 of the untreated patients was the marrow to serum muramidase ratio grossly elevated, being 10 : 1 and 12 : 1. This may be due to excessive intramedullary death of muramidase‐containing cells. Serial studies of this enzyme were carried out in 17 patients and in the majority both the marrow and the serum muramidase levels fluctuated in parallel with the changes in haematological status and returned to consistently normal levels only when patients entered complete remission. In 4 of the 7 patients who entered complete remission there was a transient rise in marrow to serum muramidase ratios following the beginning of chemotherapy. This study confirms the value of serum muramidase in the diagnosis and assessment of leukaemia. Marrow muramidase levels may occasionally provide extra information on the mechanisms of changes in intramedullary granulopoiesis.