concanavalin-a and Anorexia-Nervosa

To study the involvement of gonadotropin-releasing hormone (GnRH) in glycosylation of circulating gonadotropin isoforms in anorexia nervosa (AN), 14 amenorrhoic patients with AN, 14 age-matched volunteers in early follicular phase, and five normal-weight re-fed patients with AN were investigated under baseline conditions and after acute administration of GnRH. Plasma gonadotropins were assayed using IRMA before and after concanavalin A affinity chromatography. Baseline plasma gonadotropin levels were lower for both AN and re-fed AN patients than in controls (P<0.005). The increase in FSH and LH after GnRH administration was lower than in controls for AN (P<0.005) and re-fed AN (P<0.005 and P<0.05 respectively) patients. Percentages of total gonadotropin not bound to concanavalin A (complex carbohydrate chains) under baseline conditions were higher in patients with AN than in controls (P<0.005) but decreased after GnRH administration (P<0.001). In re-fed AN patients, the percentage of unbound FSH was higher than in controls (P<0.05), and decreased after GnRH administration (P<0.001), whereas the percentages of unbound LH were not significantly different from controls either before or after GnRH administration. These data suggest that: (a) the acute administration of GnRH induces quantitative and qualitative changes in circulating gonadotropin isoforms in both normal controls and AN patients; (b) during recovery the LH response in re-fed AN patients is associated with a glycosylation pattern that is the same as that for controls.

Topics: Adolescent; Adult; Anorexia Nervosa; Concanavalin A; Female; Follicle Stimulating Hormone; Food; Glycosylation; Gonadotropin-Releasing Hormone; Humans; Luteinizing Hormone; Reference Values; Time Factors

To investigate the relevance of glycoprotein polymorphism to gonadotropin bioactivity in vivo, plasma follicle-stimulating hormone (FSH) and luteinizing hormone (LH), 17 beta-estradiol (E2), testosterone and sex hormone binding globulin (SHBG) levels in 17 amenorrheic women affected with anorexia nervosa (14-29 years) and 10 age-matched normally cycling women were evaluated. Plasma FSH and LH levels were assayed using radioimmunoassay (RIA) and immunoradiometric assay (IRMA) methods, before and after concanavalin A-Sepharose (Con A) affinity chromatography. Significant RIA-IRMA differences in FSH and LH plasma values were present only in women with anorexia nervosa (p < 0.005). Moreover, in these patients both FSH and LH showed a reduced binding to the Con A, expressed as a percentage of unbound, suggesting altered glycosylation of these moieties. In conclusion, these findings hypothesize the involvement of glycosylation polymorphism in RIA-IRMA differences; support the usefulness of both RIA and IRMA methods in FSH and LH evaluation, before and after Con A chromatography; and suggest a new pathogenetic pathway to explain amenorrhea in anorexia nervosa.

Topics: Adolescent; Adult; Amenorrhea; Anorexia Nervosa; Chromatography, Affinity; Concanavalin A; Estradiol; Female; Follicle Stimulating Hormone; Glycosylation; Gonadotropins; Humans; Immunoradiometric Assay; Luteinizing Hormone; Pituitary Gland; Radioimmunoassay; Sex Hormone-Binding Globulin

The between-group comparison of complete lymphocyte transformation dose-response curves is complex. We have therefore derived a mathematical model of the dose-response characteristics of human mononuclear cells to stimulation by concanavalin A (ConA) and purified phytohaemagglutinin (PHA), in order to simplify such analyses. This model describes dose-response curves in terms of the magnitude of the peak response, the dose of mitogen that elicits the peak and an estimate of the range of mitogen doses which induce a response. Responses to ConA were described by the model more precisely than those to PHA. Furthermore, use of the model revealed differences between anorexia nervosa patients and healthy subjects in terms of the dose of mitogen necessary to elicit a peak response and the range of mitogen concentrations producing a response. It is proposed that this form of mathematical treatment may be of use for the comparison of lymphocyte transformation dose-response curves and for the valid rejection of suspect results.

Topics: Anorexia Nervosa; Concanavalin A; Dose-Response Relationship, Drug; Female; Humans; Interleukin-2; Lymphocyte Activation; Mathematics; Mitogens; Models, Biological; Phytohemagglutinins; T-Lymphocytes

Patients with most forms of protein-calorie malnutrition are typically more susceptible to infection. We studied the immunological consequences of a subgroup of malnourished subjects--nine patients with anorexia nervosa, who typically have a lower incidence of infection. The profiles of the patients with anorexia nervosa deviated from the reported typical profile of significantly depressed cell-mediated immunity in subjects with more common forms of protein-calorie malnutrition, demonstrating normal T-lymphocyte populations and unimpaired proliferative lymphocyte responsiveness to mitogenic stimulation with phytohemagglutinin and concanavalin A. In fact, mitogen responsiveness was significantly elevated above that of controls, and with nutritional repletion, this enhanced responsiveness regressed toward control values. Since impaired cell-mediated immunity has been consistently documented in other malnourished populations, and presumably contributes to their increased propensity toward infection, the maintenance of a relatively intact cell-mediated immune system may be an important factor separating the malnourished anorexia nervosa patient from other protein-calorie malnourished patients.

Topics: Adolescent; Adult; Anorexia Nervosa; Concanavalin A; Female; Humans; Immunity, Cellular; Infections; Lymphocyte Activation; Male; Phytohemagglutinins; Protein-Energy Malnutrition; Skin Tests; T-Lymphocytes