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Biomedical subjects

E Ohayon

Publications and source records attributed to E Ohayon.

9 recordsLinked to original sources
PubMed1979

Delayed hypersensitivity to human encephalitogenic protein as assayed by agarose leucocyte migration in multiple sclerosis patients.

Using a leucocyte migration test (Clausen's direct agarose gel migration method) hypersensitivity to human encephalitogenic protein has been examined in 50 multiple sclerosis patients (group 1), 50 healthy persons (group 2) and 25 patients with other neurological diseases (group 3). In group 1, 30 MS patients (60%) show an abnormal migration index, manifested either as inhibition or stimulation of migration; 29 controls in group 2 (58%), 11 O.N.D. patients in group 3 (44%) show an abnormal migration index. These results mean that lymphocyte hypersensitivity to myelin basic protein appears neither to be constant nor specific to multiple sclerosis. Three migration index curve types at different antigen concentration are obtained: monophasic curves within the normal index zones; monophasic curves staying in the inhibition or stimulation zone and biphasic curves with dose-effect relationship. Whatever the antigen used, this dose-effect relationship implies that the test must be carried out at different concentrations. The meaning of spontaneous sensitisation in healthy controls is discussed.

Adolescent↗
PubMed1978

Lymphocytotoxic antibodies and antiglobulins in renal allograft recipients. Correlative study with acute rejection.

In 45 patients who received kidney transplants, both homologous and heterologous human antiglobulins (anti-Ig) and HLA cytotoxic antibodies have been studied before and after transplantation and in some cases after nephrectomy. A similar study has been performed in a control group of 1,019 healthy blood donors and in 130 patients with acute or chronic glomerulonephritis. After transplantation, homologous anti-IgG were found in 60% of the patients, as compared with 3.5% in the healthy blood donors and 21% in patients with various forms of glomerulonephritis. This difference is particularly striking in sera obtained prior to nephrectomy; the presence of anti-IgG and cytotoxic antibodies in the same patient being significantly associated with early transplant failure. Anti-IgA were found in 75% of the patients with transplants and in 37% of the patients with glomerulonephritis. There was no relationship between the anti-IgA and the outcome of the graft. On the other hand, heterologous anti-Ig were unchanged in the three groups investigated. The mechanism of formation of the anti-IgG is not clear. They are probably antibodies against antigenic structures of the patient's own antibodies, previously combined with a soluble antigen or an antigen on the transplant that has undergone molecular transformation in the course of this reaction. Their pathogenic role, although not demonstrated, can be strongly suspected, and, in a practical way, screening for the anti-Ig in kidney transplant recipients could be of value as a prognostic test.

Antibodies↗
PubMed1976

[Practical interest of a micromethod for neuraminidase treatment of lymphocytes in transplantation immunology (author's transl)].

Vibrio cholerae neuraminidase treatment increases the cell sensitivity to complement and antibodies cytotoxic action. This property can be applied to the microlymphocytotoxicity technic for antibodies study in dialysed and kidney transplanted patients and for pretransplantation cross-matches. The enzymatic treatment usually employed needs a great deal of lymphocytes submitted in a second step to antibodies cytotoxic action. But this method appeared difficult to be routinely applied. We developed a simpler method consisting in treating only the lymphocytes needed to perform the test, on the reaction plate itself. This method gives the same results as the classical enzymatic treatment: the intensity of the weakly positive reaction is strongly increased, after pretreatment of cells; in certain cases, it allows one to detect cytotoxic antibodies not revealed without neuraminidase. These antibodies can be related (or not) to HLA system but practically the more important fact is the ability of this method to reveal an eventual incompatibility.

Antibodies↗
PubMedDate not supplied

[Lymphocytes HLA antigens expressivity after neuraminidase treatment (author's transl)].

Neuraminidase treatment of lymphoid cells increases the cytotoxic action of antibodies and complement on these cells. We have studied the action of 25 human alloantisera on lymphocytes of 26 healthy subjects by the Trypan blue lymphocytotoxicity technic, before and after neuraminidase treatment of cells. The results show, as a rule, an increased cytotoxicity of sera, with a higher titer and/or a more important number of positive cells. In some sera a specific cytotoxic activity is found only with neuraminidase treated cells. The antibodies often reveal an anti-HLA specificity: that specificity was previously known in the serum or, in several cases, has been found only with neuraminidase treated cells. But in some cases the new specificity does not seem to be related to the HLA system. Different hypotheses are discussed in order to explain these results and the action of neuraminidase on membranes; lastly, applications of our neuraminidase treatment method to practical problems are presented.

Antibody Specificity↗