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The possible role of phagocytosis of circulating immune complexes by neutrophils in the production of the neutropenia of Felty's syndrome has been investigated. Normal neutrophils phagocytosed massive inclusions from the sera from twelve of fifteen patients with Felty's syndrome when incubated with these sera. Such inclusions were phagocytosed from only three of fifteen patients with seropositive RA who did not have Felty's syndrome. Normal neutrophils were more effective than patient neutrophils with regard to phagocytosis of inclusions from the patients' serum suggesting a defect in phagocytic function of Felty's neutrophils. The titre of granulocyte-reactive antinuclear antibodies did not appear to be related to the degree of neutropenia. The data suggest that phagocytosis of circulating immune complexes by neutrophils may interfere with the function of these cells in combating infection and also render them susceptible to removal from the circulation thus leading to the development of neutropenia.

The effects of cyclophosphamide an antinuclear antibody levels, immune complex deposition in renal glomeruli, glomerular cell proliferation and glomerulosclerosis in the (NZB x NZW)F1 hybrid mouse have been investigated in order to better understand the mechanism of action of this drug on nephritis. Five groups of mice were injected daily with this agent (15 mg/kg) by the i.p. route over a 2-month period. Treatment periods began at 1, 3, 5, 7 and 9 months. Each group was killed at the end of the treatment period. During the last week [3H]Tdr(1 mu Ci/g) was injected daily i.p. Immune complex deposition was measured by quantification of glomerular immunofluorescent staining in both capillary loops and mesangium. Glomerular cell proliferation was quantified by measurement of the number of glomerular cells which incorporated [3H]Tdr during in vivo labelling. The number of [3H]Tdr-labelled cells in each of 100 glomeruli was counted using kidney autoradiographs of whole kidney slices. This technique provided a very reproducible and quantitative index of glomerular cell proliferation. Glomerulosclerosis was measured by determining percentage of PAS-positive material in each of 100 counted glomeruli. Immune complex deposition in the kidney preceded the glomerular cell proliferation. The proliferation reached a peak at 9 months of age. Glomerulosclerosis gradually increased with age until the animal's death. Cyclophosphamide significantly decreased antinuclear antibody levels, glomerular cell proliferation, and immunoglobulin staining in the glomeruli. Progression of glomerulosclerosis was significantly arrested. The present findings demonstrate a very significant effect of cyclophosphamide on three important pathological changes which occur in the nephritis of the (NZB x NZW)F1 hybrid mouse and provide information about possible mechanisms underlying these changes.

Binding of lymphocytes to human umbilical vein endothelial cells (EC) was quantitated by measuring adhesion of 51Cr labelled lymphocytes to endothelial cell monolayers and rosette formation between lymphocytes and EC in suspension. Mitogen stimulated human peripheral blood mononuclear cell culture supernatants and mixed lymphocyte reaction supernatants enhanced the binding of T lymphocytes to EC monolayers or suspensions preincubated with such supernatants. The active component of these supernatants appeared to be gamma interferon (IFN-gamma) since culture supernatants lost activity after heating at 56 degrees C for 60 min, exposure to pH 2.0 or treatment with anti-IFN-gamma. In addition, purified IFN-gamma increased the binding of T lymphocytes to EC (T-EC). This occurred in a concentration dependent manner when IFN-gamma was preincubated with EC but not with lymphocytes. While the optimum concentration of IFN-gamma was 250 u/ml, a significant enhancement was seen with as little as 10 u/ml. These findings suggest that IFN-gamma may play a part in the emigration of lymphocytes to perivascular chronic inflammatory sites by augmenting the adhesion of lymphocytes to the endothelium of small blood vessels.

When MRL/l mouse spleen cell culture supernatants were incubated with normal mouse spleen cells, a two-50-fold increase in anti-dsDNA activity was noted. A smaller increase in anti-ssDNA and no change in anti-TNP antibody activity were observed. This 'hidden' antibody in the MRL/l supernatants could not be revealed by DNAse digestion and could not be absorbed by a DNA cellulose column. Hidden antibody was removed from supernatants by sepharose-anti Ig. After DNAase digestion of the MRL/l supernatants, hidden anti-dsDNA could not be revealed by incubation with spleen cells. All the hidden activity was excluded by gel filtration on Sephacryl S-300 (mol. wt greater than 300,000) but was banded in the low density protein area of caesium chloride equilibrium density gradients. It was also noted that MRL/l mouse sera had hidden anti-dsDNA antibodies. Hidden antibodies were present in both the IgG and IgM classes. The revealed antibodies demonstrated impaired ability to bind Fc specific anti-Ig reagents suggesting that they were partially degraded during the incubation with mouse spleen cells. The hidden anti-dsDNA thus appears to represent a DNA-anti-dsDNA complex, perhaps of very high affinity. It may explain why anti-dsDNA but not anti-ssDNA antibodies are of pathological importance in SLE.

Immunoglobulin synthesis measured in incubated thymus tissue by the incorporation of [14C]amino acids has been studied in four thymus glands from patients with myasthenia gravis and in eight normal thymus glands from patients undergoing open heart surgery. Parallel studies have been carried out with one normal human spleen and two lymph nodes.

The tuberculin reaction was examined in the electron microscope using as antigen PPD conjugated to ferritin. The ferritin marker was rapidly localized within macrophages prior to the time of significant lymphocyte accumulation. Evidence of degenerative changes in macrophages was seen. Uptake of marker by lymphocytes was not noted. Appropriate control experiments indicated that the uptake of antigen by macrophages and subsequent macrophage degeneration were not dependent on previous sensitization. The accumulation of lymphocytes without apparent contact with unaltered antigen was interpreted as evidence that lymphocyte accumulation was a consequence of the prior interaction between antigen and macrophages.

Foreign proteins have been compared with their corresponding isologous and autologous proteins with respect to their capacity to induce inflammatory reactions at the site of injection in the skin. In contrast to the foreign proteins, which consistently produced mild reactions which were morphologically similar to the delayed hypersensitivity reaction, autologous and isologous proteins failed to induce local accumulations of inflammatory cells. The capacity of cells at the inflammatory site to phagocytoze heterologous and isologous ferritin was investigated in the electron microscope, and no qualitative differences were noted. The results are interpreted as evidence for the existence of a local mechanism capable of differentiating between foreign and autologous protein. The possible significance and role of such a mechanism is discussed.