J.W.M. Lawton

HUMAN COLOSTRAL AND BREAST MILK CELLS A Light and Electron Microscopic Study

Abstract. Colostrum and breast milk samples were obtained from 74 women, 18 of whom gave sequential samples. The mean total leukocyte count in colostrum was 3190 cells/mm3. Proportions of macrophages, polymorphs and lymphocytes varied widely; macrophages usually predominated. Serial sampling showed (1) a small fall in total counts through delivery, (2) a fall in total counts and the proportion of PMNs at the onset of lactation, (3) after 1 to 2 weeks of lactation the appearance of cytoplasmic fragments together with epithelial cells which later constituted the main cell type. It was estimated that the total number of leukocytes available to the neonate remained approximately constant during the first 2 weeks of lactation and fell thereafter. Functionally, morphologically and histochemically macrophages in colostrum and breast milk resembled macrophages elsewhere. Their ultrastructure was characterised by filiform surface projections, numerous endocytic vacuoles and lipid droplets in the cytoplasm.

Monocyte function in ageing humans.

Peripheral blood monocytes from hospitalised patients greater than 60 years of age and less than 35 years, and those from healthy normal controls less than 35 years, were tested for a range of functional and physiological properties, comprising chemotaxis under agarose, the ability to phagocytose and kill Candida albicans, adhesion to glass and spreading on glass. No significant difference was found between young and old groups, nor between hospitalized and non-hospitalized groups in respect of any parameter. There was some decline in phagocytosis and in spreading in a very old subgroup (greater than 75 years), but this was not statistically significant. This study showed that phagocytic cell function in the elderly does not decline at the same rate as the specific immune response and thus cannot directly account for the increased incidence of infection in the aged.

Lymphocyte subsets in patients with oestrogen deficiency

We have previously shown that in patients with idiopathic premature ovarian failure there were significant changes in lymphocyte subsets. To test our hypothesis that these changes were due to oestrogen deficiency we studied lymphocyte subsets in patients with oestrogen deficiency due to other causes. Blood was taken for serum oestradiol, lymphocyte counts and lymphocyte subset counts (CD2+, CD4+, CD8+ and B cells) before oestrogen replacement in 19 patients with gonadal dysgenesis, 22 patients with hypothalamic-pituitary failure and 24 healthy female control subjects. The CD4:CD8 ratio in both groups of patients was significantly lower than that in the normal control subjects while the percentages and counts of lymphocytes and CD8+ cells were significantly higher. There was a significant positive correlation between the serum oestradiol level and the CD4:CD8 ratio. These findings support the hypothesis that the changes in lymphocyte subsets are due to oestrogen deficiency.

Autoantibody formation after allogeneic bone marrow transplantation: Correlation with the reconstitution of CD5+ B cells and occurrence of graft-versus-host disease

Summary Manifestations of autoimmune diseases are common in patients who have received allogeneic bone marrow transplantation (BMT). Autoantibodies have been reported in these patients but the source and clinical significance of these autoantibodies are still obscure. In the present study the kinetics of autoantibody formation and the reconstitution of CD5+ B cells was followed in 21 patients who were submitted to allogeneic BMT. Anti‐nuclear, anti‐smooth muscle, anti‐neutrophil cytoplasmic antibodies, anti‐reticulin and rheumatoid factor were found at a frequency of 25%, 17%, 24%, 22% and 10% respectively after BMT. Anti‐double stranded DNA levels were mildly elevated in 15% of samples. The screening for anti‐extractable nuclear antigen, anti‐mitochondrial, anti‐gastric parietal cell, anti‐proteinase III, anti‐myeloperoxidase, anti‐lactoferrin antibodies was negative. The percentage and absolute count of CD5+ B cells increased with time after allogeneic BMT. Those patients with anti‐nuclear or anti‐smooth muscle antibodies had significantly higher CD5+ B cell counts than those without these two antibodies. Correlations of CD5+ B cell counts with other autoantibodies were negative. Acute graft‐versus‐host disease (GVHD) occurred in eight of the patients and chronic GVHD in four patients, but the frequency of autoantibodies had no relationship with the occurrence of acute or chronic GVHD.Abbreviations: BMT, bone marrow transplantation; GVHD, graft‐versus‐host disease; ANA, anti‐nuclear antibody; ANCA, anti‐neutrophilcytoplasmic antibody; SMA, anti‐smooth muscle antibody.

Characterization of macrophage function in Mycobacterium lepraemurium-infected mice: sensitivity of mice to endotoxin and release of mediators and lysosomal enzymes after endotoxin treatment

Summary Mycobacterium lepraemurium (MLM) infection increases the sensitivity of mice to lipopolysaccharide (LPS) as do infections with other intracellular parasites. Tumour necrosis factor (TNF), lymphocyte activating factor (LAF) and increased levels of various lysosomal and cytoplasmic enzymes were found in serum samples taken 2 h after intravenous injection of a small dose of LPS suggesting that damage to a variety of cell types, including macrophages, had occurred. Sera from moribund MLM‐infected mice not injected with LPS also demonstrated significant levels of TNF compared with controls. Intravenous injections of silica into leprous mice also led to increased levels of serum lysosomal and cytoplasmic enzymes but did not give rise to a significant amount of TNF or LAF. Moreover, in contrast to LPS treatment, the injection of silica did not lead to the death of leprous mice. These findings suggest that the phagocytic cells of the infected animals did not contribute to the production of these mediators after LPS challenge. Rather, the non‐phagocytic granuloma macrophages or other unidentified cell types seemed to provide the main source of the monokines TNF and LAF in vivo in the present model. These mediators may have important implications for the immunopathology of MLM infection.

Protease inhibitor phenotypes and serum alpha-1-antitrypsin levels in patients with COPD: A study from Hong Kong

Objective:  Many studies have suggested that an imbalance of protease activation and inhibition might result in COPD with emphysema. Levels of alpha‐1‐antitrypsin (α1‐AT), the key protease inhibitor, are genetically determined by alleles that present in many phenotypes/subtypes, some of which are associated with deficiency of the protein. We prospectively evaluated the prevalence of the protease inhibitor (Pi) alleles and phenotypes together with the serum α1‐AT levels in Chinese patients with COPD.

The effect of in vivo modulation of macrophage activities on Mycobacterium lepraemurium infection

During the early stage of Mycobacterium lepraemurium (MLM) infection in mice, the mononuclear phagocyte system (MPS) was activated non-specifically as demonstrated by enhanced listericidal activity. Such listericidal activity could be further increased by Corynebacterium parvum treatment, indicating that MLM was not a good MPS stimulant. Corynebacterium parvum treatment conferred only marginal protection upon mice during MLM infection, as shown by the slight but significant prolongation of survival time and decreased bacillary load. In contrast, mice could not control splenic Listeria growth in the later stage of infection regardless of C. parvum treatment. Adoptive transfer of Listeria-immune spleen lymphocytes, however, did significantly suppress splenic Listeria growth. The significance of these findings is discussed.

MEASUREMENT OF ANTI-DSDNA: A COMPARATIVE STUDY OF TWO ELISA AND THE CRITHIDIA ASSAY

Summary We compared the measurement of anti-dsDNA by a commercial ELISA test (DIASTAT), an in-house ELISA and the Crithidia luciliae assay in cross-sectional sera samples of 209 systemic lupus erythematosus (SLE) patients and 64 patients with a variety of rheumatological, autoimmune and non-autoimmune diseases in Hong Kong. The Crithidia assay was found to be the least sensitive (17%) but most specific (95%) method for detection of a positive result in SLE patients. The DIASTAT assay has a higher sensitivity (68%) but lower specificity (80%) than the in-house ELISA test (32% sensitivity and 89% specificity). The positive predictive value of the three assays are comparable at 90–92% while DIASTAT had the highest negative predictive value (44%). There was good linear correlation (r = 0.7) between the two ELISAs. ELISA can serve as a useful screening test for anti-dsDNA in SLE patients and doubtful cases can then be confirmed by another method such as radioimmunoassay.Abbreviations: SLE, systemic lupus erythematosus.

Further studies on immunological parameters in gestational trophoblastic neoplasia

SummaryThe total blood lymphocyte counts, T-cell counts, B-cell counts, percentage of T cells bearing Fc receptors for IgG (TG), lymphocyte responses to phytohaemagglutinin and concanavalin A and serum IgA levels were measured in 15 patients with hydatidiform mole, 32 patients with malignant trophoblastic disease, 30 pregnant controls, and 34 normal non-pregnant controls. The mean percentage of TG was similar in all four groups but the mean absolute number of TG in patients with malignant trophoblastic disease was significantly lower than that in normal non-pregnant controls, due to the lower mean lymphocyte count and T-cell count in the former group. An immune profile score based on the T-cell count, B-cell count, lymphocyte response to mitogens, and serum IgA level was useful in predicting the subsequent development of malignant trophoblastic disease in patients with hydatidiform mole but was not helpful in predicting resistance to chemotherapy in malignant trophoblastic disease.

Evaluation of phagocytic function in Mycobacterium lepraemurium infection

Infection of mice with Mycobacterium lepraemurium caused significant functional alterations of the mononuclear phagocyte system. Accelerated clearance of sheep red blood cells was consistently demonstrated throughout the infection and the infected mice showed progressive anaemia. Infected mice showed an enhanced ability to limit growth of phagocytosed Listeria monocytogenes in spleens during the early stages of infection, whereas moribund leprous mice lost this ability. Autoradiography showed that uninfected Kupffer cells and splenic macrophages of moribund mice could still phagocytose Listeria, suggesting that MLM infection did not affect the capacity of Listeria to localize to macrophages but interfered in some way with subsequent killing of such bacteria. The possible mechanisms underlying these observations are discussed.