Comparison of lymphocyte populations bearing surface immunoglobulins in avian bone marrow, bursa, spleen and thymus.

Rabbit anti-chicken gamma-globulin was labeled with 125I and then incubated with cells from the bursa, thymus, spleen, and bone marrow of 4- and 8-week old birds. The same procedure was carried out on 11-week-old agammaglobulinemic chickens. Autoradiography revealed that the majority of large, medium, and small bursal lymphocytes bind the antibodies while labeled lymphocytes of each type in the spleen and thymus never exceeded 11 or 4 percent, respectively. Labeled medium and small lymphocytes in the bone marrow increased from 4.2 and 1.7%, respectively, at 4 weeks of age, to 9.5 and 8.8%, respectively, at 8 weeks of age. Labeled lymphocytes of all sizes were completely absent in all tissues of agammaglobulinemic chicks, including the marrow. Therefore, the increase in frequency of labeled lymphocytes in the bone marrow with age may be a result of recruitment of cells from the bursa of Fabricius. The majority of lymphocytes in the bone marrow do not label. Therefore, lymphocytes from the bone marrow may be T cells, subsets of B cells, or neither T or B cells.     

Comparison of class I- and II-restricted T cell recognition of the identical peptide.

There is structural and functional evidence that both class I- and II-restricted T cells recognize short processed peptides bound to MHC molecules. Although the structural conformation of bound peptides remains unknown, no evidence of distinct structural motifs of class I- or class II-restricted peptides has been described. Conversely, two algorithms proposed to predict T cell epitopes, and based on primary amino acid sequence or tertiary structure, are both compatible with many observed class I- and class II-restricted peptides. We previously identified eight class I-restricted peptides which were also recognized by class II-restricted T cells. Based on functional and direct binding studies, additional examples of peptides with both class I and II restrictions have been identified. In this study, we have directly compared the fine specificity of T cell recognition of a single epitope in a single mouse strain in the context of both class I- and class II-restricted responses. Based on a panel of analogue peptides with amino acid substitutions and peptides of various lengths, we observed several striking similarities in the recognition patterns of both class I- and class II-restricted T cells. In addition, some characteristics of recognition were different in the two systems indicating that the recognition processes were similar but not identical.     

Persistent centrilobular necroses in hepatic allografts

A biopsy study of 60 allografts from 53 patients after orthotopic liver transplantation (OLT) revealed prominent centrilobular necrosis (CN) in 18% of the grafts that were suitable for analysis. The lesions often had a "punched-out" appearance, sometimes with unusual features such as giant cell formation. Persistent CN developed 4 weeks to 6 months after OLT, and persisted in two cases for 2 years and longer. In some instances, CN disappeared or healed by scarring. We found no association between CN and rejection arteritis or arteriopathy. Ductopenic (chronic) rejection subsequently occurred in six of eight livers with CN. Overall, patients with persistent CN had a worse prognosis than control patients. A comparison of cases with matched controls failed to reveal significant differences with respect to perioperative factors such as ischemia time, immunologic test results such as lymphocyte crossmatches, drug administration--in particular, of azathioprine, frequency of cellular (acute) rejection or infection episodes, or frequency of complications affecting major hepatic vessels or bile ducts. Morphologic evidence suggests that in some instances, rejection-induced endotheliitis/phlebitis of hepatic vein branches may lead to sinusoidal outflow blockage, sinusoidal dilatation, and dropout of hepatic cell plates. Although potentially reversible conditions such as ischemia or adverse drug reactions are among the possible causes of CN, severe rejection leading to ductopenia appears to be the most important underlying condition. Thus, presence of CN in repeated biopsy specimens from allografts should be considered a warning sign of irreversible rejection.     

C1-esterase inhibitor blocks T lymphocyte proliferation and cytotoxic T lymphocyte generation in vitro

We have previously shown that activated C1s complement and activated T cells cleave beta2-microglobulin (beta2m) in vitro leading to the formation of desLys58 beta2m. This process can specifically be inhibited by C1-esterase inhibitor (C1-inh). Furthermore we showed that exogenously added desLys58 beta2m in nanomolar amounts to a one-way allogenic mixed lymphocyte culture (MLC) increased the endogenous production of IL-2 and the generation of allo-specific cytotoxic T lymphocytes. C1-inh was purified from fresh human plasma and added to human or murine MLC and mitogen-stimulated lymphocyte cultures grown in the presence of complement-inactivated serum. Read-outs were cell proliferation, lymphokine production and development of T cell-mediated cytotoxicity. We found that addition of C1-inh to MLC and mitogen- exposed murine and human lymphocyte cultures inhibited proliferation, the development of allospecific cytotoxic activity, and changed the endogenous production of IL-2, IL-4, IL-10, IL-12 and IFN-gamma. These data clearly demonstrate a regulatory function of C1-inh on T cell- mediated immune functions.      

The CTLA-4 gene region of chromosome 2q33 is linked to, and associated with, type 1 diabetes. Belgian Diabetes Registry

Susceptibility to autoimmune insulin-dependent (type 1) diabetes mellitus is determined by a combination of environmental and genetic factors, which include variation in MHC genes on chromosome 6p21 (IDDM1) and the insulin gene on chromosome 11p15 (IDDM2). However, linkage to IDDM1 and IDDM2 cannot explain the clustering of type 1 diabetes in families, and a role for other genes is inferred. In the present report we describe linkage and association of type 1 diabetes to the CTLA-4 gene (cytotoxic T lymphocyte associated-4) on chromosome 2q33 (designated IDDM12). CTLA-4 is a strong candidate gene for T cell- mediated autoimmune disease because it encodes a T cell receptor that mediates T cell apoptosis and is a vital negative regulator of T cell activation. In addition, we provide supporting evidence that CTLA-4 is associated with susceptibility to Graves' disease, another organ- specific autoimmune disease.      

Autosomal glycogenosis of liver and muscle due to phosphorylase kinase deficiency is caused by mutations in the phosphorylase kinase beta subunit (PHKB)

Glycogen storage disease due to phosphorylase kinase deficiency occurs in several variants that differ in mode of inheritance and tissue- specificity. This heterogeneity is suspected to be largely due to mutations affecting different subunits and isoforms of phosphorylase kinase. The gene of the ubiquitously expressed beta subunit, PHKB, was a candidate for involvement in autosomally transmitted phosphorylase kinase deficiency of liver and muscle. To identify such mutations, the complete PHKB coding sequence was amplified by RT-PCR of RNA isolated from blood samples of patients and analyzed by direct sequencing of PCR products. The characterization of mutations was complemented by PCR of genomic DNA. In one female and four male patients, we identified five independent nonsense mutations (Y418ter; R428ter; Y974H+E975ter; Q656ter in two cases), one single-base insertion in codon N421, one splice-site mutation affecting exon 31, and a large deletion involving the loss of exon 8. Although these severe translation-disrupting mutations occur in constitutively expressed sequences of the only known beta subunit gene of phosphorylase kinase, PHKB, they are associated with a surprisingly mild clinical phenotype, affecting virtually only the liver, and relatively high residual enzyme activity of approximately 10%.      

Is fecundability associated with month of birth? An analysis of 19th and early 20th century family reconstitution data from The Netherlands

The relationship between fecundability and month of birth was investigated in a cohort of 1526 women who married between 1802 and 1929, using only women whose first marriage occurred before the age of 35 years. On the basis of their time to pregnancy (TTP, calculated as time between wedding and first birth minus gestational length), women were categorized into two groups: fecunds (TTP up to 12 months or prenuptial conceptions, n = 1348) and subfecunds (TTP >18 months, n = 118). By use of logistic regression, cosinor functions with a period of 1 year or 6 months and variable shift and amplitude were fitted through the monthly odds of subfecunds versus fecunds. The best fitting curve was unimodal, with a zenith in September (P = 0.13 for H0: no differences). Exclusion of childless women (n = 36, minimum follow-up 5 years) from the subfecunds led to a similar curve (P < 0.01), while childless women, as compared with fecunds, showed a birth distribution that was best represented with a bimodal curve with zeniths in January and July (P = 0.06). This study provides evidence for the existence of differences in fecundability by month of birth. The cause of this relationship is unclear, but may lie in a melatonin-dependent circannual variability of the quality of the oocyte.