Characterization of the receptor for IgM present on human B lymphocytes.

The presence of a receptor for the Fc of IgM (muFcR) was demonstrated on the pathological B cells of all of sixteen patients with hairy-cell leukaemia and most, but not all, of twenty-four cases of chronic lymphocytic leukaemia, by a rosette method employing ox erythrocytes sensitized with purified IgM (EAm). This muFcR was also demonstrated on a small population of normal human mononuclear cells from peripheral blood. Pathological B cells with this receptor (Bm) simultaneously expressed a different and distinct receptor for the Fc of IgG, and were detectable without preincubation in medium containing foetal calf serum (FCS). The muFcR on B cells was blocked by Fc5mu and IgM, but not by F(ab')2mu fragments, or by IgG, whether monomeric or aggregated. Monomeric IgM and IgM bound to its antigen blocked much more effectively than pentameric IgM. B cells also possessed surface immunoglobulin and the Ia-like P29, 34 antigen, and an antiserum to this antigen blocked the muFcR. The muFcR on B cells differs in a number of ways from the muFcR reported on T cells, and these differential characteristics are discussed in some detail. The muFcR was rapidly shed and resynthesized when washed Bm cells were maintained in medium not containing FCS and the general importance of this phenomenon in any study of muFcR is considered. It is suggested that Bm cells are memory cells and that the muFcR plays a part in the immune response.     

Interleukin 7 and T cell receptor signals regulate homeostasis of CD4 memory cells

Immunological memory depends on the long-term maintenance of memory T cells. Although the factors that maintain CD8 T cell memory are well understood, those responsible for CD4 memory are not well defined. We have shown here that interleukin 7 (IL-7) was an important survival factor for CD4 memory T cells that together with T cell receptor (TCR) signals regulated homeostasis of the CD4 memory population in lymphopenic conditions and in the intact immune system. Thus, IL-7 contributes to the maintenance of all naive and memory T cell subsets, and therefore controls the overall size of the T cell pool.     

Borrelia burgdorferi and Interleukin-1 Promote the Transendothelial Migration of Monocytes In Vitro by Different Mechanisms

A prominent feature of Lyme disease is the perivascular accumulation of mononuclear leukocytes. Incubation of human umbilical vein endothelial cells (HUVEC) cultured on amniotic tissue with either interleukin-1 (IL-1) or Borrelia burgdorferi, the spirochetal agent of Lyme disease, increased the rate at which human monocytes migrated across the endothelial monolayers. Very late antigen 4 (VLA-4) and CD11/CD18 integrins mediated migration of monocytes across HUVEC exposed to either B. burgdorferi or IL-1 in similar manners. Neutralizing antibodies to the chemokine monocyte chemoattractant protein 1 (MCP-1) inhibited the migration of monocytes across unstimulated, IL-1-treated, or B. burgdorferi-stimulated HUVEC by 91% ± 3%, 65% ± 2%, or 25% ± 22%, respectively. Stimulation of HUVEC with B. burgdorferi also promoted a 6-fold ± 2-fold increase in the migration of human CD4⁺ T lymphocytes. Although MCP-1 played only a limited role in the migration of monocytes across B. burgdorferi-treated HUVEC, migration of CD4⁺ T lymphocytes across HUVEC exposed to spirochetes was highly dependent on this chemokine. The anti-inflammatory cytokine IL-10 reduced both migration of monocytes and endothelial production of MCP-1 in response to B. burgdorferi by approximately 50%, yet IL-10 inhibited neither migration nor secretion of MCP-1 when HUVEC were stimulated with IL-1. Our results suggest that activation of endothelium by B. burgdorferi may contribute to formation of the chronic inflammatory infiltrates associated with Lyme disease. The transendothelial migration of monocytes that is induced by B. burgdorferi is significantly less dependent on MCP-1 than is migration induced by IL-1. Selective inhibition by IL-10 further indicates that B. burgdorferi and IL-1 employ distinct mechanisms to activate endothelial cells.     

Factors affecting transfer of experimental autoimmune thyroiditis in rats

Actively induced experimental autoimmune thyroiditis in inbred Lewis rats was comparable using standard Freund's complete adjuvant (FCA) and Perrin's modification of FCA. However, adoptively transferred disease using lymph node cells from rats immunized with Perrin's FCA was significantly more severe. With this adjuvant, and pertussis vaccine as co-adjuvant, transfer was uniformly successful when at least 480 × 10⁶ lymph node cells were taken 10 days after immunization and recipients were killed 3 days after transfer. Lymphocytic infiltrates were seen in recipient thyroids as early as 18 hours after transfer. Whole body irradiation of the recipients at 550 r reduced the severity of transferred disease. The frequency and severity of lesions were higher when the lymph node cells were first incubated with low doses of antigen. Thymectomy of the recipients decreased the severity of transferred disease. Under the conditions tested, transfer of disease could not be accomplished by antiserum alone, even using thyroidectomized donors. Administration of an early immune serum with sensitized lymph node cells significantly depressed the severity of transferred disease, while a late antiserum increased it.     

Comparison of Two Culture Methods for Detection of Tobramycin-Resistant Gram-Negative Organisms in the Sputum of Patients with Cystic Fibrosis

A culture method utilizing quantitative plating on antibiotic-containing media has been proposed as a technique for the detection of tobramycin-resistant organisms that is more sensitive than standard methods. Typical sputum culture methods quantitate the relative amounts of each distinct morphotype, followed by antibiotic susceptibility testing of a single colony of each morphotype. Sputum specimens from 240 cystic fibrosis patients were homogenized, serially diluted, and processed in parallel by the standard method (MacConkey agar and OF basal medium with agar, polymyxin, bacitracin, and lactose) and by plating on antibiotic-containing media (MacConkey agar with tobramycin added at 25 microg/ml [MAC-25] and 100 microg/ml [MAC-100]). MICs of tobramycin were determined for all Pseudomonas aeruginosa isolates by broth microdilution. Growth of P. aeruginosa on MAC-25 was considered to be equivalent to a tobramycin MIC of > or = 16 microg/ml, and growth on MAC-100 was considered to be equivalent to a tobramycin MIC of > or = 128 microg/ml. Analysis of method-specific detection rates showed that tobramycin-containing medium was more sensitive than the standard method for the detection of tobramycin-resistant P. aeruginosa, Stenotrophomonas maltophilia, and Achromobacter xylosoxidans but was less sensitive for the detection of Burkholderia cepacia than the standard method. When MICs for P. aeruginosa that grew on tobramycin-containing medium were tested by broth microdilution, the MICs for 28 of 121 strains (23%) growing on MAC-25 and 22 of 56 strains (39%) growing on MAC-100 were MICs < 16 and < 128 microg/ml, respectively. Addition of a tobramycin-containing MacConkey plate to the routine media for sputum culture may provide additional, clinically relevant microbiologic data.     

A randomised controlled trial to test the feasibility of a collaborative care model for the management of depression in older people

BACKGROUND: Depression is the most common mental health disorder in people aged over 65 years. Late-life depression is associated with chronic illness and disability. AIM: To investigate the feasibility of a collaborative care model for depression in older people in a primary care setting. DESIGN OF STUDY: Randomised controlled trial with 16-weeks follow up. SETTING: A primary care trust in Manchester. METHOD: Participants were 105 people aged 60 years or older who scored 5 or more on the Geriatric Depression Scale; 53 were randomly allocated to an intervention group and 52 to a usual care group. The intervention group received care managed by a community psychiatric nurse who delivered an intervention comprising a facilitated self-help programme with close liaison with primary care professionals and old-age psychiatry according to a defined protocol. The usual care group received usual GP care. A nested qualitative study explored the views of the health professionals and patients regarding the acceptability and effectiveness of the intervention. RESULTS: The main outcome measure was recovery from depression. Patients in the intervention group were less likely to suffer from major depressive disorder at follow up compared with usual care (0.32, 95% confidence = interval = 0.11 to 0.93, P = 0.036). The qualitative component of the study demonstrated the acceptability of the intervention to patients. CONCLUSION: A model of collaborative care for older people with depression, used in a primary care setting with a facilitated self-help intervention is more effective than usual GP care. This study demonstrates that the implementation of a collaborative care model is feasible in UK primary care and that the intervention is effective and acceptable to patients.     

Purification and immunological characterization of a GroEL-like protein from Bordetella pertussis.

A GroEL-like protein from Bordetella pertussis was purified. This protein was found to have the tetradecameric subunit structure typical of the GroEL family of proteins and to contain epitopes similar to those of other members of this family, including a human GroEL-like protein. Active immunization of neonatal mice with the B. pertussis GroEL-like protein provided little protection against an aerosol challenge with B. pertussis. Antibodies to this protein were elicited in mice by a standard diphtheria-tetanus-pertussis (DTP) vaccine but not by an experimental acellular pertussis vaccine. Since the Bordetella GroEL-like protein was found to contain epitopes similar to those on the mammalian analog, the potential exists that vaccination with standard DTP vaccines may induce antibodies which react with the mammalian GroEL analog.     

Migration of lymphoblasts to the small intestine. III. Strain differences and relationship to distribution and duration of Trichinella spiralis infection.

In NIH strain mice, in which the majority of Trichinella spiralis are located in the anterior half of the small intestine early in the enteral phase of infection, enhanced localization of mesenteric lymphoblasts, nylon wool separated mesenteric T-lymphoblasts and even oxazolone sensitized peripheral lymphoblasts is most prominent in the anterior region of the small intestine. As the worms move to the posterior half of the small intestine, enahnced localization of lymphoblasts is observed in that region only. In BALB/c mice, in which most of the worms are located in the posterior half of the small intestine, enhanced localization of lymphoblasts is primarily in that region. Expulsion of the worms commences within 2--3 days of a large increase in the number of lymphoblasts localizing in the anterior region of the small intestine in NIH strain mice and likewise follows a second and larger increase in the number of lymphoblasts localizing in the posterior region of the small intestine of BALB/c mice.     

Modulation of Bcl-2 family proteins in primary endothelial cells during apoptosis

We studied the expression of Bcl-2 family proteins during cytokine- and verotoxin (VT)-induced apoptosis in primary human umbilical vein endothelial cells (HUVECs). Our experiments demonstrated that high initial expression of Bcl-2 protein was significantly downregulated in HUVECs treated with IFN-gamma whereas TNF-alpha gave a less pronounced decrease in Bcl-2 level. Treatment with the combination of cytokines was more efficient in downregulating Bcl-2 protein. HUVECs pretreated with cytokines and incubated with VT gave a further significant decrease in Bcl-2 level. Simultaneous measurement of Bcl-xl level did not reveal any significant changes. Bax protein was upregulated in HUVECs stimulated with TNF-alpha alone or in combination with IFN-gamma. However, addition of VT did not give any further increase in Bax level suggesting that Bax upregulation is more important for cytokine- rather than VT-mediated apoptosis. Total endothelial cell growth factor deprivation gave a significant increase in apoptosis accompanied by a decrease of Bcl-2 in apoptotic cells while Bcl-xl and Bax levels were unaffected. Our data indicate that anti-apoptotic protein Bcl-2 and pro-apoptotic protein Bax are reciprocally regulated during apoptosis, whilst Bcl-xl is essentially unaffected. This implies that Bcl-2/Bax ratio rather than Bcl-xl controls apoptosis in primary endothelial cells.