The effect of concanavalin-A (Con A) stimulation on lymphocyte subpopulations

It has been shown that suppressor T lymphocytes can be activated by plant mitogens as Con A. In order to see if there is any change in lymphocyte surface markers in addition to functional activity, lymphocyte subpopulations (E, EA gamma, EAC rosette forming cells) were determined in 18 healthy controls and 16 patients with ataxia-telangiectasia (AT) after 18-24 hour incubation of lymphocytes with or without Con A (10 micrograms/ml per 2 x 10(6) lymphocytes). Without any incubation, the percentage of EA gamma-RFC was higher and E-RFC was lower in AT patients than in controls. In healthy controls the percentage of EA gamma-RFC significantly increased after incubation with Con A, while the patient group did not show any significant difference. In contrast, the percentage of E-RFC cells in AT group showed significant increase after Con A incubation, while this difference was not significant in healthy controls. There was no significant difference in percentage of EAC-RFC with or without Con A incubation in healthy controls and AT patients. These differences between patient and control groups can be explained by the different features in circulating lymphocyte subpopulations.

Epstein-Barr-virus-carrying lymphoma in a patient with ataxia-telangiectasia

An undifferentiated lymphocytic lymphoma of mesenteric lymph nodes occurred in a young boy with ataxia-telangiectasia. Two independent tests, Epstein-Barr virus (EBV)-cRNA/DNA hybridisation and EBV DNA/DNA reassociation kinetic analysis, showed 53 and 68 EBV genome equivalents per cell respectively, which was compatible with an EBV-genome-carrying tumour. Whether this was a polyclonal lymphoproliferation or a monoclonal tumour could not be determined owing to lack of suitable material. The presence of EBV genomes should be sought in lymphomas arising in ataxia-telangiectasia and other immunodeficiencies.

Clinical and immunological studies in a case of selective complete C1q deficiency

A 10-year-old male with recurrent skin lesions and chronic infections was found to have a selective deficiency of C1q after functional analysis of all complement components. The addition of highly purified human C1q to the patient's serum restored C1 activity, indicating the presence of C1r and C1s and the absence of C1q. Titration of highly purified C1q with patient serum as a source of C1r and C1s resulted in a linear dose-response curve. The undetectable CH50 activity temporarily returned to normal within a few hours of plasma infusion, but the C1 titres were still only 1–3% of normal. Following plasma administration, the peak of C1q activity was reached after 30 min and returned to undetectable levels within 24 hr. The patient serum was not anti-complementary when incubated with normal serum. Nine members of the family, including the parents and two healthy siblings, were subjected to complement studies and HLA typing. The C1 titres and CH50 activity were found to be normal in all except the paternal grandmother who showed reduced levels of all the complement components. There was no linkage for the gene of C1q deficiency and HLA antigens. Among the various laboratory studies performed, anti-smooth muscle antibodies, immune complexes and anti-HBsAg antibody were found to be positive. The child died of a disease compatible with septicaemia. Post mortem tissue studies by light, fluorescent and electron microscopy have shown the presence of a mesangioproliferative glomerulonephritis.

Epstein-Barr virus-related antibody patterns in ataxia-telangiectasia

Epstein-Barr virus-related antibody titres were determined in twenty-seven patients with ataxia-telangiectasia (AT) and twenty-two healthy members of their families, in twenty-two patients with other diseases, among them ten with Behçet's disease and ten with various primary immune deficiencies, and fifteen healthy members of their families, and in twenty-three unrelated healthy controls. The AT patients showed an increased incidence (55.6%) of high antibody titres (greater than or equal to 1:320) to viral capsid antigen (VCA), and also a high incidence (48.2%) of antibodies to Epstein-Barr virus (EBV) induced early antigens (EA), but low titres (less than 1:10) of antibodies to the EBV-associated nuclear antigen (EBNA) in 44.2% of the cases. The geometric means of anti-VCA were three-to four-fold higher, and of anti-EBNA six-fold lower, than those of the control groups. The patients with the other diseases did not differ significantly from the controls except for a higher incidence of anti-EBNA titres of less than 1:10 (38.1% vs 4--5%). AT patients with low anti-EBNA titres tended to have more advanced T cell deficiencies than AT patients with moderate anti-EBNA titres, as detected by counts of total lymphocytes and E-rosetting cells, and skin test responses. The results support the hypothesis that a functioning T cell system is required to release EBNA from EBV genome-carrying cells for initial and maintained production of anti-EBNA.

Possible involvement of endogenous histamine in the myotropic effect of clonidine on the isolated rabbit aorta

Clonidine has a contractile effect in the isolated rabbit aorta which can be blocked by alpha-adrenergic antagonist, phentolamine. Histamine H1-receptor blocker, mepyramine, partly antagonizes its myotropic effect and histamine H2-blocker, metiamide, potentiates it, implying a histaminergic component in the response. Inhibition of histamine synthesis by histidine decarboxylase inhibitor, GYKI 11.121, reduces clonidine-induced contraction in this preparation, while diamine oxidase inhibition by aminoguanidine potentiates it. This is indirect evidence of the possibility of de novo histamine synthesis by clonidine, which may take part on the contractile effect of the drug in the rabbit aorta.

Histocompatibility (HLA) factors in ataxia telangiectasia

In the recent studies conducted in patients with various types of primary immunodeficiency diseases, an increased frequency of HLA-A1 or HLA-A2 antigens was reported. In order to determine the frequency of the histocompatibility antigens in ataxia telangiectasia (A-T), HLA typing was carried out in 30 patients with A-T along with their 23 parents and 4 siblings. The results were compared with 138 healthy controls. That study showed no significant difference for the frequencies of 19 HLA antigens of the A and B loci between the controls and A-T patients or their parents-siblings.

Transfer factor therapy in ataxia--telangiectasia

The effects of weekly doses of transfer factor in four patients with ataxia--telangiectasia were investigated following a total course of 2 months therapy. Transfer factor administration showed no influence on the absolute lymphocyte counts, T-cell rosettes or antibody titres to EBV, but it caused conversion of skin-test reactivity and production of MIF to various antigens. There was a dissociation in blastic transformation response, the skin-test responses and MIF production. Serum interferon levels were low before, and 2, 6 and 24 hr after, therapy. Clinically no improvement in infections was observed following transfer factor therapy.