Investigation of the kinetics of histidine-rich protein 2 and of the antibody responses to this antigen, in a group of malaria patients from India.

Although immunological tests based on the detection of histidine-rich protein 2 (HRP2) from the parasites permit the rapid diagnosis of Plasmodium falciparum malaria, such tests are not yet sufficiently sensitive to detect every bloodsmear-positive case. Some individuals infected with P. falciparum may appear test-negative because of the presence of anti-HRP2 antibodies in their sera. A longitudinal follow-up of HRP2 antigenaemia and antibody responses to this antigen has now been conducted in a group of 45, bloodsmear-positive malaria cases of various ages, both during acute infection with P. falciparum and after antimalarial treatment. Pre-treatment, 'day-0' samples of fingerprick blood were tested for HRP2 (in antigen-capture ELISA) and for antigen-specific IgM and IgG (in indirect ELISA). The patients were then treated, with standard doses of chloroquine, before being retested, for HRP2 and anti-HRP2 antibodies, on days 7, 15 and 28. The level of antigenaemia, which on day 0 was found to be positively correlated with parasitaemia (r = 0.741; P < 0.001), had only fallen by an insignificant amount by day 7 but showed further, significant falls between days 7 and 15 (P < 0.001) and between days 15 and 28 (P < 0.01). Although no significant relationship was observed between the blood concentrations of HRP2 and anti-HRP2 IgM or IgG on days 0 or 7, the level of HRP2 antigenaemia was found to be positively correlated with the concurrent titre of anti-HRP2 IgM on day 15 (r = 0.612; P < 0.001) and day 28 (r = 0.501; P < 0.001). The titres of HRP2-specific IgG gradually increased over the 28 days of follow-up but were not found to be significantly correlated with the decreasing levels of HRP2 antigenaemia. When the 45 day-0 samples of blood were tested for HRP2 in a rapid diagnostic test (RDT), three appeared negative, probably because of interference from the circulating, free, anti-HRP2 antibodies in the plasma. The three RDT-negative samples were significantly different from the 42 RDT-positive, having relatively low HRP2 antigenaemias (P < 0.001) and relatively high titres of anti-HRP2 IgM (P < 0.05) and IgG (P < 0.001). Control samples of blood, from four patients infected with P. vivax and five healthy, normal individuals, were considered ELISA-negative for HRP2 and anti-HRP2 IgM or IgG. It appears that, during human infection with P. falciparum, serum levels of HRP2 antigen remain elevated for at least 7 days post-treatment, despite the host's development of antigen-specific immune responses both before and after treatment.

New dimensions in vaccinology: A new insight.

The development of vaccines to prevent infectious diseases has been one of the most important contributions of biomedical sciences. Increasing understanding in biochemistry, molecular biology, molecular genetics and related fields have provided an opportunity for the development of new generation vaccines that are based on rational design approaches. This is possible because of proper understanding of the microbial-genetics, biochemistry, host-pathogen interaction and recent developments in molecular immunology. Another important improvement made in the quality of vaccine production is the incorporation of immunomodulators or adjuvants with modified delivery vehicles viz liposomes, Iscoms and microspheres apart from alum being used as a gold standard. This article reviews the art of vaccination from Jenner period to present day context highlighting all the developments made at each stage of the vaccine development. Various criteria have been discussed regarding the selection of epitopes that expand B & T cells, its linkage with other accessory cells of the immune system, means to overcome MHC linked immune unresponsiveness, enhanced antigen processing and presentations that specially induce either helper or cytotoxic or mucosal immune responses were critically discussed.

Expression of costimulatory molecules (CD80, CD86, CD28, CD152), accessory molecules (TCR alphabeta, TCR gammadelta) and T cell lineage molecules (CD4+, CD8+) in PBMC of leprosy patients using Mycobacterium leprae antigen (MLCWA) with murabutide and T cell peptide of Trat protein.

In leprosy, cell-mediated immunity (CMI) is more significant than humoral response to eliminate intracellular pathogen. T cell defect is a common feature in lepromatous leprosy (LL) patients as compared to tuberculoid type (TT) patients. For efficient initiation of CD4+, T cell response requires T cell receptor (TCR) activation and costimulation provided by molecules on antigen-presenting cells (APC) and their counter receptors on T cells. In our previous study, the defective T cell function in LL patients was restored to a proliferating state with the release of TH1 type cytokines using mycobacterial antigen(s) with two immunomodulators (Murabutide (MDP-BE) and T cell epitope of Trat protein of Escherichia coli) by presenting the antigen in particulate form in vitro to PBMC derived from leprosy patients. This observation prompted us to study the expression of the costimulatory molecules (CD80, CD86, CD28, CD152), other accessory molecules (TCR alphabeta/gammadelta) and T cell lineage molecules (CD4+ and CD8+) during constitutive and activated state of peripheral blood mononuclear cells (PBMC) derived from normal and leprosy individuals using different formulations of Mycobacterium leprae total cell wall antigen (MLCWA), Trat and MDP-BE using flow cytometric analysis. An increased surface expression of CD80, CD86 and CD28 but decreased CD152 expression was observed when PBMC of normal, BT/TT (tuberculoid) and BL/LL (lepromatous) patients were stimulated in vitro with MLCWA+MDP-BE+Trat peptide using liposomal mode of antigen delivery, while opposite results were obtained with the antigen alone. Antibody inhibition study using antihuman CD80 or CD86 completely abolished the T cell lymphoproliferation, thereby reconfirming the importance of these costimulatory molecules during T cell activation/differentiation. Though the liposome-entrapped antigen formulation has no effect on expression of alphabeta/gammadelta T cell receptor, the constitutive levels of TCR gammadelta were high in lepromatous patients. Thus, TCR bearing gammadelta appears to have a negligible regulatory role in peripheral blood of leprosy patients. The percentage of cells positive for CD4+ are increased in inducible state in all the three groups, while CD8+-positive cells were decreased in LL patients, thereby reconfirming the fact that priming of CD4+ cells are necessary for producing final effector functions. Lastly, intracellular cytokine staining experiment indicated that CD4+ cells are the major producers of IFN-gamma but not NK cells. The study highlights the reversal of T cell anergy especially in lepromatous patients through the modulation of costimulatory molecule expression under the influence of Th1 cytokines, i.e., IL-2 and IFNgamma.

Yersinia pestis F1 antigen: a correlation between antibody titres and subclass distribution with differential avidity in different inbred mouse strains.

The F1 antigen of Yersinia pestis has been identified as one of the protective antigens. The present study aims to generate anti-F1 antibodies in mice of different genetic background and to compare antibody profile, isotype distribution and avidity measurement in sera to observe the pattern of immune response as a strategy to develop F1-based immunogen for plague. The study indicated that, although all the immunological parameters were identical, the avidity of the antibodies was considerably different with various strains of mice. Thus, this study may have an implication while developing F1-based vaccine for plague and avidity measurement definitely has a role for antibody function.

Cytogenetic evidence for involvement of B lymphocytes in acquired idiopathic sideroblastic anemias.

We studied the cellular distribution of an unusual chromosomal abnormality, an interstitial deletion of the long arm of chromosome 13, in the peripheral blood lymphocytes of two patients with acquired idiopathic sideroblastic anemia (AISA). We found no metaphases containing the 13q- abnormality in preparations of phytohemagglutinin (PHA)-stimulated lymphocytes from either patient. In both cases, however, some metaphases from Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines contained the clonal karyotypic abnormality. These observations indicate that B lymphocytes but not T cells are expressed as members of the clonal cohort of cells. Our results strongly suggest that the initial pathogenetic events that led to expansion of the 13q- clone occurred in a progenitor cell capable of giving rise to both hematopoietic and B lymphoid cells.

Four restriction fragment length polymorphisms revealed by probes from a single cosmid map to chromosome 19.

We have discovered and characterized a compound polymorphic locus on chromosome 19, defined by an arbitrary genomic DNA segment cloned into a cosmid vector. Four different restriction fragment length polymorphisms with minor allele frequencies equal to or greater than 10% are revealed by Southern hybridization of subclones of cosmid 1-13 with TaqI, MspI, BamHI, and HindIII digests of human DNAs. Seventy-two percent of unrelated individuals are heterozygous at one or more loci, and seven of the 24 possible haplotypes occur with frequencies of 3%-38%. Using a somatic cell hybrid panel, we have mapped this locus to 19p13.2----19q13.3, whereas in situ hybridization suggests the probe is on 19p. Taken together, these results suggest localization to 19p13.2----19cen. The locus revealed by probes from cosmid 1-13 has been designated D19S11.

Localization of the beta-globin gene to 11p15 by in situ hybridization: utilization of chromosome 11 rearrangements.

Chromosome preparations from four subjects, one normal 46,XY male and three patients with different rearrangements of chromosome 11: 46,XX,del(11)(p11.2----p15.1), 46,XY,inv(11)(p13q24.2), and 46,XY,rec(11)inv(11)(p13q24.2) pat, were utilized for in situ hybridization studies with a tritium-labeled cDNA probe containing a beta-globin insert. Using the hybridization technique described by Harper and Saunders (1981), there were 1-2 grains over each labeled metaphase. Of 360 cells scored, 88 were labeled over chromosome 11, band p15 (24%). Approximately half of the chromosome 11s labeled from the abnormal patients were the del(11) or inv(11). These results exclude the beta-globin locus from 11p11----p14, since these bands were not present in the deleted 11, and assign it to 11p15. This is in agreement with the recent exclusion data of de Martinville and Francke (1984) and Junien (1984), and suggestive assignment data of Morton et al. (1984).

Bone marrow transplantation for severe combined immune deficiency in an infant with chimerism due to intrauterine-derived maternal lymphocytes: donor engraftment documented by chromosomal marker studies.

Chromosomal heteromorphisms defined by the quinacrine banding technique were used to identify the maternal origin of 46,XX lymphocytes present in the blood of a male infant with severe combined immune deficiency disease. These chromosomal markers were also used to document the engraftment by donor lymphocytes from the sister and the concurrent disappearance of maternal lymphocytes after a successful bone marrow transplantation. Donor lymphocytes were detected by this technique 6 days after transplantation, earlier than is usually possible with other marker systems and before definite evidence of immunoreconstitution. Maternal lymphocytes persisted in the patient's peripheral blood for a prolonged period of time, being detectable 172 days after transplantation. Analysis of T-lymphocyte- and B-lymphocyte-enriched populations after transplantation documented lymphoid chimerism with T-lymphocytes of donor origin and B-lymphocytes of both patient and donor origin, demonstrating prolonged persistence of patient B-lymphocytes and suggesting that the patient's immune defect is primarily at the T-lymphocyte level.

Translocation(X;Y)(p22.33;p11.2) in XX males: etiology of male phenotype.

Analysis of G-banded prometaphase chromosomes from three XX males revealed extra bands on the distal end of one X short arm. These bands were similar both in size and staining properties to the distal Y short arm of their fathers (in the two cases examined) and also to other chromosomally normal males. The extra material on the abnormal X chromosomes was not C- or G-11 positive in the two cases examined, suggesting that the proximal Y long arm was not present. Previous karyotype-phenotype correlations with structurally altered Y chromosomes provided evidence for localization of male determinants on the Y short arm. The present findings in XX males provide support for more precise localization, to bands p11.2 leads to pter of Y short arm.