Covalent modification of protein by drugs may disrupt self-tolerance leading to lymphocyte activation. Determination of the threshold required for this process has not hitherto been possible. We have therefore performed quantitative mass spectrometric analyses to define the epitopes formed in tolerant and hypersensitive patients taking the β-lactam antibiotic piperacillin and the threshold required for T-cell activation. A hydrolysed piperacillin hapten was detected on 4 Lys residues of HSA isolated from tolerant patients. The level of modified Lys541 ranged from 2.6-4.8%. Analysis of plasma from hypersensitive patients revealed the same pattern and levels of modification 1-10 days after commencement of therapy. Piperacillin-responsive skin-homing CD4+ clones expressing an array of Vβ receptors were activated in a dose, time and processingdependent manner; analysis of incubation medium revealed that 2.6% of Lys541 in HSA was modified when T-cells were activated. Piperacillin-HSA conjugates that had levels and epitopes identical to those detected in patients were shown to selectively stimulate additional CD4+ clones, which expressed a more restricted Vβ repertoire. To conclude, the levels of piperacillin-HSA modification that activated T-cells are equivalent to the ones formed in hypersensitive and tolerant patients, which indicates that threshold levels of drug antigen are formed in all patients. Thus, the propensity to develop hypersensitivity is dependent on other factors such as on the presence of Tcells within an individual's repertoire that can be activated with the β-lactam hapten and/or an imbalance in immune regulation.

Drug hypersensitivity involves the activation of T cells in an HLA allele-restricted manner. Because the majority of individuals who carry HLA risk alleles do not develop hypersensitivity, other parameters must control development of the drug-specific T cell response. Thus, we have used a T cell-priming assay and nitroso sulfamethoxazole (SMX-NO) as a model Ag to investigate the activation of specific TCR Vβ subtypes, the impact of programmed death -1 (PD-1), CTL-associated protein 4 (CTLA4), and T cell Ig and mucin domain protein-3 (TIM-3) coinhibitory signaling on activation of naive and memory T cells, and the ability of regulatory T cells (Tregs) to prevent responses. An expansion of the TCR repertoire was observed for nine Vβ subtypes, whereas spectratyping revealed that SMX-NO-specific T cell responses are controlled by public TCRs present in all individuals alongside private TCR repertoires specific to each individual. We proceeded to evaluate the extent to which the activation of these TCR Vβ-restricted Ag-specific T cell responses is governed by regulatory signals. Blockade of PD-L1/CTLA4 signaling dampened activation of SMX-NO-specific naive and memory T cells, whereas blockade of TIM-3 produced no effect. Programmed death-1, CTLA4, and TIM-3 displayed discrete expression profiles during drug-induced T cell activation, and expression of each receptor was enhanced on dividing T cells. Because these receptors are also expressed on Tregs, Treg-mediated suppression of SMX-NO-induced T cell activation was investigated. Tregs significantly dampened the priming of T cells. In conclusion, our findings demonstrate that distinct TCR Vβ subtypes, dysregulation of coinhibitory signaling pathways, and dysfunctional Tregs may influence predisposition to hypersensitivity.

BACKGROUND: In pregnancy, several physiological changes occur that lead to decrease in the level of hemoglobin. Anemia during pregnancy is a major public health concern in underdeveloped nations, with a high rate of morbidity and death among pregnant women. Inadequate prenatal care, a lack of information about the nutritional requirements of pregnant women, and general low socioeconomic circumstances all contribute to these high rates of morbidity and death. As pregnant women’s and husbands’ education levels increased, the frequency and severity of anemia decreased in the investigated community of pregnant women. AIM: This study aims to find out the level of knowledge about anemia in pregnancy among adult females attending primary health care centers (PHCCs) and to find out if there is any association between sociodemographic characteristics of adult females and knowledge about anemia in pregnancy. METHODS: A cross-sectional study with analytic component conducted in four PHCCs in Al-Adhamiya Health District during a period of 4 months from December 1, 2020, to April 1, 2021. It included 400 females aged between 18 and 45 years attending the selected PHCCs for any complaint. The data had been collected through the distribution of well-designed questionnaire including two parts: Participants’ sociodemographic characteristics and knowledge parts. RESULTS: In this study, overall knowledge score of the participants about anemia in pregnancy showed that 60% had fair knowledge. There were statistically significant associations between knowledge score and age of females, marital status, educational level, occupation, and parity. CONCLUSION: The majority of Iraqi adult females have fair and acceptable levels of knowledge about anemia in pregnancy. Younger age, being single, low educational level, unemployed, and low parity were associated with worst level of knowledge.