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Five commercial screening assays for HIV-1, evaluated for their usefulness in detecting infection in high-risk groups in the East African country of Djibouti, produced varying degrees of performance when compared to Western blot and immunofluorescence confirmatory assays. In this population with a low prevalence of HIV infection (16/599), two enzyme-linked immunosorbent assays (ELISA; Abbott and Elavia) and two rapid assays (cambridge latex agglutination and Du Pont's HIV-CHEK) exhibited less than optimal sensitivities. However, with the exception of Elavia, these assays displayed excellent specificities. The fifth test (Serodia gelatin agglutination) produced the highest sensitivity (0.938) and negative predictive value but the lowest specificity and positive predictive value of all five tests. False positive reactions, which occurred only with the Elavia and Serodia tests, could not be explained on the basis of early infection in patients or cross-reactions with the related retroviruses HIV-2 and HTLV-I. We conclude that none of the five tests alone is sufficient in this testing situation, but that a combination of tests could satisfy most requirements for identifying HIV-1 reactive and non-reactive sera.

The HLA-D region of the human major histocompatibility complex (MHC) has been shown to be homologous to the murine I region in terms of both structure and function. Both regions encode class II MHC molecules which restrict T-lymphocyte interactions with antigen-presenting cells. We have recently described the MHC restriction and antigen specificities of human T-lymphocyte clones directed at strain A influenza virus. The majority of T-lymphocyte clones recognized antigen in the context of cell surface interaction products encoded by HLA-D/DR genes. However, a few clones recognized antigen presented by cells histoincompatible for D/DR antigens. We report here that some of these clones recognized viral antigens in association with antigens encoded by genes identical with or closely linked to the recently described secondary B-cell (SB) locus of the MHC. This is the first report that SB-restricted antigen recognition may form an integral part of normal, human immune responses.

The restoration of sensitivity to azathioprine of athymic (nu/nu) mouse splenic rosette-forming cells (RFC) has been used by others to assay thymic hormone. These previous studies have led to the conclusion that a major factor in the development of autoimmunity in New Zealand (NZ) mice and patients with systemic lupus erythematosus (SLE) is the premature loss of thymic hormone. We have studied the mouse rosette assay and find that poly A-Poly U and single stranded DNA, in addition to thymosin, restored azathioprine sensitivity to nu/nu RFC. Thus, other substances may mimic thymic hormone, perhaps via the cyclic AMP system. Furthermore, antibodies to T cells were found to interfere with the assay. Sera from old NZ mice which contain naturally occurring thymocytotoxic antibodies (NTA) failed to restore azathioprine sensitivity. Small quantities of NTA prevented normal sera from functioning in the assay. We conclude that the role of thymic hormone(s) in the development of autoimmunity in NZ mice and patients with SLE must be completely reevaluated.

A seroepidemiologic survey was conducted among 773 male soldiers living in five urban locations in Sudan to study the prevalence of and risk factors for HIV-1 and hepatitis B transmission. Twenty-eight per cent of the study population were born and raised in southern Sudan, an area bordering Kenya, Zaire and Uganda, whilst 72% of the study subjects were from northern Sudan. Seventy-eight per cent of the study population had serologic evidence of past hepatitis B infection, and 13 soldiers were confirmed positive for HIV-1 antibody. All 13 HIV-positive soldiers had recently been deployed in southern Sudan. Multivariate analysis indicated an association between living in southern Sudan and both hepatitis B (odds ratio 8.2) and HIV-1 infection (odds ratio 14). Additionally, sexual relations with prostitutes (odds ratio 1.5) and medical injections for schistosomiasis (odds ratio 2.72) were independent predictors of hepatitis B markers in this military population. The findings of this study suggest that sexual promiscuity is a risk factor for hepatitis B transmission in Sudan. They also indicate one possible route for the spread of HIV-1 from central to northern Africa.

A serosurvey was conducted in Port Sudan and Suakin, Sudan in October and March 1987 to determine the prevalence and risk factors associated with the transmission of hepatitis B, human immunodeficiency virus type 1 (HIV-1), and syphilis among sexually active heterosexuals on the coast of Sudan. A total of 536 subjects, including 202 female prostitutes, 95 long-distance truck drivers, 103 soldiers, 72 Ethiopian refugees, and 54 Sudanese outpatients, were enrolled in the study. Seventy-eight percent (202/259) of the female study subjects were engaged in prostitution, and 57% (157/277) of the men admitted to prior sexual relations with prostitutes. Serologic markers for hepatitis B and syphilis were detected in 68% and 17% of the entire study population, respectively. In contrast, antibody to HIV-1 was detected in none of the 536 sera tested. Risk factors found to be independently predictive of hepatitis B infection by multivariate analysis included prostitution, positive serology for syphilis, and a history of anti-schistosomal therapy. The absence of HIV-1 infection among the prostitutes enrolled in this study is in marked contrast to the current AIDS epidemic in neighboring sub-Saharan countries, suggesting that HIV-1 has not been widely introduced on the coast of Sudan. The high prevalence of serologic markers to hepatitis B and syphilis, however, indicates a potential for HIV-1 in this region.

Primary cell cultures from the livers of mice infected with Schistosoma mansoni were prepared and cells with the appearance of fibroblasts by light microscopy were isolated. Collagen synthesis was estimated by measuring incorporation of 14C-proline into collagenase-sensitive proteins for both culture media and cell layers. Coculture of splenic T cells from infected mice with these hepatic fibroblasts caused greater selective and specific reduction in collagen production than did coculture using spleen cells from normal mice. There was a parallel inhibition in collagen within the cell layer which indicates that the marked decrease in collagen production was due to inhibition of synthesis and not related to changes in solubility or secretion. Primary culture of mouse skin fibroblasts showed similar responses to coculture but an established fibroblast line, 3T3, was unresponsive. Inflammatory cells appear to influence hepatic fibroblasts isolated under our experimental condition in several ways, such as opposite effects on collagen synthesis and cell proliferation.

A serosurvey involving 656 individuals revealed that hepatitis A infection was virtually universal in Djibouti in 1987, and more than half of the people investigated had serum markers of hepatitis B infection. The rate of chronic HBsAg carriers was 7.3% and was higher for males than for females. Both HBsAg and anti-HBs positivity rates were directly related to increasing age. No uniform mechanism could be found to account for transmission of the hepatitis B virus, and no correlation was noted between HBV-marker status and sexual promiscuity or the classic blood exposure risks. However, a significant association existed between the abuse of khat and the chronic HBsAg carrier state.

Monoclonal antibodies (DA-2 and CA-2) and xenoantisera (rabbit anti-human, p23,30) specific for HLA-DR framework determinants were added to primary and secondary mixed lymphocyte cultures. Although such antisera were shown to inhibit primary MLC, primed lymphocytes were much less sensitive to the blocking effects of these antibodies. In the studies shown here, the concentration of antibody required to inhibit primary MLC reactions was 0.1-1.5 micrograms/ml).

In attempting to evaluate the mechanisms responsible for susceptibility to the inductive increase in splenic complement receptor-positive (CR+) cells following exposure to 2450-MHz microwaves, it was found that sensitivity to microwave-induced CR+ cell increases was under genetic control. In particular, evidence was accumulated suggesting that regulation was under the control of a gene or genes closely associated with but outside of the mouse major histocompatibility complex (H-2). All responsive strains of mice tested were of the H-2k haplotype, while mice of the H-2a, H-2b, H-2d and H-1i5 haplotypes were refractory to the microwave-induced increases in CR+ cells. By utilizing certain H-2k strains of mice that were genetically unable to respond to endotoxin, we were able to show that these strains of mice responded to microwaves, but not to endotoxin, by increasing CR+ cells. Microwave-induced increases in CR+ cells were not mimicked by the intraperitoneal injection of hydrocortisone. Athymic mice responded to microwave exposure, indicating that this event was not regulated by the T-cell population. Mice less than eight weeks old were found not to be susceptible to exposure to 2450-MHz microwaves. These studies indicate that microwaves do induce changes in the population of cells with specific cell-surface receptors, that susceptibility to these changes is under genetic control, and that it is unlikely that endotoxin, corticosteroids, or regulatory T cells play a significant role in the mechanisms regulating these increases.

T helper cell factors (HF) have been preparated against protein and synthetic antigens by restimulating in vitro induced helper cells with small amounts of antigen. HF when tested in vitro are antigen specific and capable of replacing T cells, initiating a thymus dependent IgM response. In the in vivo adoptive transfer assay HF is capable of replacing T helper cells and is active at very high dilution, inducing both IgM and IgG responses. When tested on unirradiated DNP primed animals the HF was able to initiate a thymus dependent anti-hapten response, comparable to that seen with helper T cells, of both IgM and IgG class. It was also shown that HF acts on anti-Thy 1 treated spleen cells. The results indicate that antigen specific helper factors may be one of the physiologic mediators of T-B interactions in intact animals.

We have previously shown that co-culture of T cell enriched spleen lymphocytes can reduce collagen synthesis and stimulate proliferative activity by liver fibroblasts from S. mansoni infected mice. The present study examines which subset of T cells is responsible for this modulation. Co-culture of fibroblasts with the total T cell population lead to significant stimulation in fibroblast proliferative activity and a significant decrease in the incorporation of 14C-proline into collagenase-sensitive protein. There was virtually no effect on total incorporation of 14C-proline in non-collagen proteins. An additional significant increase in fibroblast proliferative activity and another significant decrease in collagen synthesis accompanied by a 2-fold increase in non-collagen protein production was noted when fibroblasts were co-cultured with Lyt-1+ cells. Co-culture of fibroblasts with Lyt-2+ cells did not differ significantly from co-culture with total T cells. Mitomycin treatment of the lymphocytes blunted their specific effects, suggesting that proliferation of T cells is required for maximal exertion of their regulatory activity. These results suggest that the T cells which mediate these effects belong to the Lyt-1+ helper class and are distinct from the Lyt-2+ suppressor cells.

The efficacy of the 2 antimicrobial compounds, erythromycin and trimethoprim-sulphamethoxazole, were compared in the treatment of the clinical symptoms of cholera and the eradication of Vibrio cholerae O1 organisms from the stools of patients infected with tetracycline-resistant strains. 47 patients with a clinical diagnosis of cholera, without prior antibiotic therapy, were included in the trial and received either erythromycin, trimethoprim-sulphamethoxazole, or a placebo twice daily. The mean number of vibrios per gram of stool decreased from 5.2 x 10(8) +/- 0.3 per ml to 0 within 36 h of admission following either erythromycin or trimethoprim-sulphamethoxazole therapy, while organisms persisted in placebo-treated controls for more than 7 d. Clinically there was a significant reduction in the number of diarrhoeal stools per day and duration of diarrhoea in the erythromycin-treated group compared with the placebo-treated controls. During the study an isolate resistant to trimethoprim-sulphamethoxazole but sensitive to erythromycin was obtained. As an adjunct to oral rehydration therapy, erythromycin may serve as an effective alternative treatment for cholera, especially in areas where trimethoprim-sulphamethoxazole resistance may be emerging.

One hundred patients (71 males and 29 females) with bacterial meningitis were randomly assigned into two therapeutic regimens. Patients in group I were intravenously given ceftriaxone (CRO: Rocephin) to adults and intramuscularly to children once daily in a dose of 100 mg/kg/day. Patients in group II received ampicillin 160 mg/kg/day and chloramphenicol (AMCL) 100 mg/kg/day (i.v. to adults and i.m. to children) every 6 h. No significant difference was observed between the two therapeutic regimens with regard to mortality, time taken to become afebrile, fully alert and sequelae. Seven patients in the CRO group died compared to 10 in the AMCL group. The mean number of days taken to become afebrile were 3.4 and 3.5, and to become fully alert 3.9 and 3.5 for groups I and II, respectively. CRO administered in a single daily dose appears to be as effective as a combination of ampicillin and chloramphenicol given every 6 h in the treatment of acute bacterial meningitis. However, the once daily dose is more appropriate for use especially in areas where nursing care is limited.

With anti-Ly antisera and complement it has been possible to demonstrate that cytotoxic effector cells generated in vitro against allogeneic cells carry the alloantigen Ly-5 and Ly-6. The studies show that antisera directed against the Ly-6 antigens, together with complement, eliminate essentially all of the killer cells, of the appropriate strain, while killing only 50 to 60% of Thy-1+ cells. Anti-Ly-5 antsera and complement lysed 55 to 65% of Thy-1+ cells and killed a significant portion, but not all, of the cytotoxic cells. The later finding was investigated in more detail since it suggested a degree of heterogeneity within the killer cell subpopulation. However, the data did not support that conclusion, at least for allogeneic killer cells.

Harvest of human bone marrow directly from freshly resected bone provides purer preparations of marrow than can be obtained by the conventional technique of multiple aspirations from the iliac crests. In particular, directly harvested marrow is much less heavily contaminated with peripheral blood lymphocytes, a known source of mature T cells. Because of the possible relevance of these contaminating T cells for cadaveric bone marrow transplants, the best source of human marrow harvested directly from bone has been studied. Human bone marrow was harvested from 46 surgical specimens and 9 cadaveric tissue donors. Vertebral bodies provided the best source of bone marrow with average yields of 3.1 +/- 1.6 X 10(9) cells per vertebra. When entire ilia were removed and processed for marrow, an average of 1.6 +/- 1.0 X 10(9) cells was obtained. Surgically resected ribs yielded lower amounts of marrow with a mean cell number of 3.2 +/- 2.6 X 10(8) per rib. Isolation of bone marrow mononuclear cells from these preparations by density gradient centrifugation resulted in a loss of 45% of the starting cells. Human bone marrow was found to contain 5-6% T cells before gradient separation and these cells were immunologically competent as measured in vitro by responses to mitogens and alloantigens. This technique may be useful in obtaining human bone marrow for both immunologic studies and allogeneic transplantation.

Using normal subjects, it was found that the 'Active Rosette Test' is both reproducible and consistent if performed exactly as described by Wybran et al. (1972). Variations in incubation time, centrifugal force while sedimenting rosettes, resuspension time after centrifugation, SRBC lymphocyte ratio, and increasing concentrations of fetal calf serum all produced marked deviations in test results. Rosette inhibition studies using a specific anti-T cell antisera showed inhibition of 'active' and total rosettes at the same level, suggesting that there are no marked variations in surface T antigens among respective T cells. Unless differences in functional activities can be demonstrated between the 'active' rosette-forming cells and the other T cells, the test will be of an empiric nature.

Patients presenting at the Juba Teaching Hospital, either with fever of undetermined origin or with a clinical cause of fever, gave evidence of exposure to a wide range of viral and rickettsial agents. Serological tests showed high antibody levels to flaviviruses (56.9%) and alphaviruses (29.2%), with lesser levels of bunyamweraviruses (3.8%), Rift Valley fever (2.3%), and sandfly fever (0.75%). Flavivirus exposure was significantly associated with clinical evidence of liver disease; repeated exposure to flaviviruses was particularly prevalent in those with poor sanitation and who had received previous injections. A significant focus of Ebola and Marburg exposure in Juba has been identified. Clinical evidence of liver disease was evident in 37% of patients studied, and 24.6% were HBsAg positive. The first 2 HIV-positive individuals from the southern Sudan are reported, including one with clinical AIDS. A high prevalence of positive antibodies to Rickettsia typhi in the population indicated that murine typhus was common locally. This study indicates the need for further public health measures in the southern Sudan to control the spread of these infections.

A dot-enzyme-linked immunosorbent assay (dot-ELISA) was developed as a fast and field applicable antibody detection tool for the diagnosis of human fascioliasis. The assay is performed using partially purified antigens from a species of Fasciola at 180 ng protein/dot (2 microliters) and serum samples at 1:20 dilution (1 microliter). Dot-ELISA results completely agreed with those of micro-ELISA. Antigen-coated nitrocellulose sheets stored for 3 mo at -20 C showed results identical to fresh sheets. Sera from patients with fascioliasis (n = 30) and other parasitic or viral infections (n = 120) were compared with sera from healthy controls (n = 14). Ninety samples can be tested within 90 min. The sensitivity, specificity, and speed of the assay may justify its use in laboratory and field studies.

Two equine antithymocyte globulin preparations were studied with respect to their relative rosette inhibition activity after storage at 4 and 25 C. After storage at 4 C for 48 months no activity loss was observed; 25 C storage resulted in fragmentation and eventual loss of relative rosette inhibition activity. A third preparation was studied by monkey skin graft prolongation. During a 1-year period, there was no loss of immunosuppressive activity as measured by this method and the rosette inhibition assay.

The complete amino acid sequence of papain-solubilized HLA-B27, an antigen that presents a very strong association to the development of ankylosing spondylitis, has been determined. The overall sequence homology with the cross-reactive allelic products HLA-B7 and HLA-B40 (Bw60) is 93% and 92%, respectively. Half of the differences between HLA-B27 and -B7 are located in segments 63-83 and 113-116. Most of the known HLA class I antigens are different in these segments, and it is suggested that the corresponding residues may be involved in the alloantigenic determinants of HLA-B27. A free cysteine residue is present at position 67, and it is at least partially exposed to solvent. In addition, other differences are found in various areas of the two N-terminal domains. The comparison with available HLA class I sequences allows an evaluation of their contribution to the antigenic polymorphism of these molecules. The relevance of these data is discussed in connection with the mapping of functional sites of HLA class I antigens and with the association between HLA-B27 and ankylosing spondylitis.

A method for marking viable cells which allows highly sensitive detection of the cells in mixed populations is described. Viable tumor cell lines or normal lymphocytes were stained with the supravital DNA stain Hoechst 33342 (H342) and seeded into human bone marrow. Examination of the marrow mixtures with an inverted fluorescence microscope allows detection of a single H342-stained cell in 1 million marrow cells. H342 staining does not cause significant changes in cell viability or in the sensitivity of the cells to complement mediated lysis. Counterstaining the mixture with trypan blue quenches H342 fluorescence in nonviable cells, limiting detection to only viable cells.

This was a collaborative project between education and service that focused on teaching patients with COPD and resulted in the development and testing of an evaluation and teaching tool. The process is described and analyzed using an adaptation of Lancaster's framework for successful collaboration.

The antigen receptor on human T lymphocytes consists of two variable immunoglobulin-like glycoproteins, alpha and beta, which occur in association with three invariable T3 membrane proteins. In humans two of these proteins, T3-gamma and T3-delta, are glycoproteins of relative molecular mass (Mr) 25,000 (25K) and 20,000 (20K), respectively, while the third, T3-epsilon, is a 20K non-glycosylated protein. On the surface of murine T cells, a non-glycosylated protein dimer composed of 17K subunits (T3-zeta) is found associated with the T-cell receptor alpha and beta chains and the three T3-like polypeptide chains. It is generally accepted that major histocompatibility complex-restricted antigen recognition is a function of the alpha-beta heterodimer. This has led to the postulation that the proteins of the T3 complex are involved in the signal transduction that immediately follows antigen recognition via the antigen receptor. Events believed to be involved in early T-cell activation, such as rapid increases in phosphatidylinositol turnover and free intracellular calcium, can be triggered by antibodies directed against either the T3 complex or the clonotypic receptor. We have previously reported our findings on the cloning of the complementary DNA and genomic structure encoding both the human and murine 20K glycoprotein, T3-delta (refs 11-13). We now present our results on the cloning of the cDNA encoding the human 20K non-glycosylated chain, T3-epsilon.

The Ly and Ia phenotypes of T lymphocytes involved in the in vitro generation of helper and suppressor cells were identified. The precursors of both cells are found in adult thymectomized spleen. Helper precursors are Ly-1+2-3-Ia-, while suppressor precursors are Ly-1-2+3+Ia-, although the suppressor effector is Ia+. In both cases a second 'amplifier' cell is required for differentiation of precursors to occur. This cell is found in anti-lymphocyte serum-treated spleen and has the phenotype Ly-1+2+3+Ia-.

Children with diarrhea presenting to a Government Rehydration Center in Aswan, Egypt, were investigated to determine the etiology and clinical presentation of acute childhood diarrhea in southern Egypt. Among 126 outpatients and 25 inpatients with diarrhea (mean age 18 months), enterotoxigenic Escherichia coli (ETEC) (17% of cases), Cryptosporidium (9%), Salmonella spp. (7%), Campylobacter jejuni/coli (7%), and Shigella spp. (5%) were the most common enteropathogens identified during the high incidence season of July. Enteropathogens were isolated as often from inpatients as outpatients, except for Salmonella spp. and Cryptosporidium, which were recovered more often from inpatients. Salmonella-infected children, in particular, were more ill, feverish, and dehydrated on presentation than other children, resulting in more frequent hospitalization. Except for Salmonella-infected children, children with acute diarrhea usually presented without severe dehydration, which may have been due to frequent initiation of oral rehydration therapy (ORT) by mothers trained by local health care providers. A potential environmental source of ETEC was identified in clay water storage containers commonly used in this area.