CD3+/CD30+ circulating T lymphocytes are markedly increased in older subjects with Down's syndrome (Trisomy 21).

CD3+/CD30+ circulating T lymphocytes were found to be increased in the blood of individuals with Down's syndrome (DS; trisomy 21). This finding appears to be related to age as the numbers of CD3+/CD30+ T cells were dramatically enhanced in the circulation of older DS subjects. Since CD30 antigen expression is considered to be a marker of T-helper-2 (Th-2) activation, and Th-2+ cells are associated with certain human pathologies, our data may in some way explain the enhanced susceptibility of DS patients to infections, malignant diseases and autoimmunity.

Gamma delta T cells are decreased in the blood of children with Bordetella pertussis infection.

The biological role of T cell receptor (TCR) gamma delta bearing cells is not yet fully understood. We studied 12 children with Bordetella pertussis infection and 12 age- and sex-matched healthy controls. Patients with whooping-cough yielded significantly lower relative and absolute numbers of blood TCR-gamma delta + cells than normal controls (both p < 0.001). It is suggested that the depletion of circulating gamma delta T cells in patients with Bordetella pertussis infection might be the result of the dispatch of these cells to the site of inflammation, i.e. the bronchial mucosa. Interestingly, other human lung diseases, such as allergic bronchial asthma and sarcoidosis display similar pulmonary phenotypical features.

Gamma delta T-cell subset distribution in human semen from fertile donors.

PROBLEM: Gamma delta T-cell subset distribution has not been fully investigated in normal human semen. METHODS: We therefore carried out experiments by using a direct immunofluorescence staining technique followed by two-color cytofluorimetric analysis on mononuclear cell (MC) suspensions from ejaculates of ten healthy, fertile volunteers. Autologous peripheral blood MC were simultaneously analyzed and the results used for statistical comparison. RESULTS: The proportion of normal human semen lymphocytes bearing the gamma delta T-cell receptor for antigen was greatly increased compared with autologous circulating counterparts. Interestingly, the rise was mainly due to an overexpansion of cells expressing V delta 1 gene-encoded determinants on their surface. This contrasts with the normal blood picture, where most gamma delta T cells express V delta 2 conformational epitopes. CONCLUSIONS: The numerical and phenotypical differences in semen gamma delta T lymphocytes provide further evidence of a defined migrating lymphocyte subset balance in anatomically and physiologically distinct areas of the body. Their functional role, in terms of both helper and suppressor-cytotoxic activities in the nonsterile proximal portions of the male genital tract, now needs to be explored in detail.

CD26 and CD31 surface antigen expression on human colostral T cells.

The expression levels of CD26 and CD31 surface antigens, two adhesion/activation molecules with helper and suppressor activities, respectively, were found to be significantly higher on human colostral T cells (CD3+) than in autologous peripheral blood samples. These findings provide further phenotypical evidence that immune system T lymphocytes are compartmentalized in the mammary gland late in pregnancy and during lactation. The question of whether these overexpanded T lymphocyte populations in breast milk modulate in situ, either by enhancing or suppressing, the cellular and/or humoral immune response of the suckling infant remains to be answered. Additional studies are, therefore, needed to explore this intriguing field concerning the immunology of the colostrum.

CD26 surface antigen expression on peripheral blood T lymphocytes from children with Down's syndrome (trisomy 21).

A phenotypical analysis carried out by two-colour flow cytometry showed that the proportion of circulating CD4+ T lymphocytes co-expressing the membrane-associated ectoenzyme dipeptidyl peptidase IV (CD26 antigen), a functional collagen receptor involved in T-cell triggering through its interaction with the CD45 protein tyrosine phosphatase, was significantly lower in 28 children with non-translocated trisomy 21 (Down's syndrome) (DS) than that calculated in the bloodstream of 27 age- and sex-matched healthy controls. Agonist anti-CD26 monoclonal antibodies (MoAbs), such as anti-1F7, not only modulate the surface expression of this molecule, but also enhance the proliferative activity of normal human T cells via the CD3- and CD2-mediated activation pathways. T-lymphocyte proliferation induced by antigen or polyclonal T-cell activators, including anti-CD3 or -CD2 MoAbs, is severely impaired in DS. Although the physiological ligand of CD26 surface structure is unknown, the fact that CD4+ T lymphocytes found in the blood of trisomic subjects are mostly CD26- (anti-1F7-) suggests that their faulty mitogenic response may be due to phenotypical and, perhaps, strictly correlated functional abnormalities.

Lymphocytes bearing the gamma delta T-cell receptor in acute toxoplasmosis.

Although the relative and absolute numbers of CD3+ cells (T lymphocytes) were similar in eight children with acquired Toxoplasma gondii infection and 10 uninfected age- and sex-matched healthy controls, the proportion of cells bearing the gamma delta T-cell receptor was significantly higher in the subjects with acute toxoplasmosis. The great majority of gamma delta T cells from the infected patients expressed covalently bound gamma delta chains on their surface, i.e. were BB3+ lymphocytes. Since the gamma delta T-cell subsets exert both restricted and unrestricted major histocompatibility complex cytotoxicity, further research is needed to elucidate the role of gamma delta T cells in the control of this coccidian protozoan infection.

Lymphocytes bearing the gamma/delta T-cell receptors in Down's syndrome.

Subjects with Down's syndrome (DS), or trisomy 21, have an increased susceptibility to infections, malignant diseases and autoimmune phenomena. Various arms of the immune system are severely impaired in trisomic patients. We found that the proportion of blood lymphocytes bearing the gamma/delta T-cell receptor (TCR) was significantly higher in adults with trisomy 21 than in age- and sex-matched healthy controls. Interestingly, the increase was mainly due to an over-expansion of cells which bear non-covalently bound gamma/delta chains on their surface. This contrasts with the normal blood picture, where the great majority of gamma/delta T cells express the disulphide-linked form of the TCR. The fact that trisomic gamma/delta T cells are both numerically and phenotypically unbalanced provides further evidence that immunological abnormalities are integral features of DS.

Plasma cell generation inhibition in lymphocyte cultures containing cerebrospinal fluid from children with central nervous system viral infections.

Plasma cell generation in pokeweed mitogen-pulsed lymphocyte cultures was markedly suppressed when the experiments were carried out by adding cell-depleted cerebrospinal fluid (CSF) from 5 acute aseptic meningitis or meningoencephalitis children known to have an overexpanded cell population with the suppressor-cytotoxic T-cell surface phenotype in their CSF. In contrast, B-cell terminal differentiation was not affected by the addition of CSF from 5 control children with non-neurological diseases, thereby indicating that CSF from central nervous system virus-infected children contains soluble factors which are themselves capable of exerting regulatory influences on immunocompetent cells.