Differences in alloimmune response between elderly and young mice.

OBJECTIVE: The upper age of renal transplant recipients is rising on the transplant wait list. Age-dependent immune responsiveness to new antigens has not been thoroughly studied. This study used a mouse model of alloantibody response to neoalloantigen to study age-related differences. METHODS: Transgenic huCD20-C57BL/6 mice were immunized intraperitoneally with BALB/c splenocytes (2.5 × 10(7)) at baseline and 1 month. Plasma samples were collected at baseline and 1 and 2 months after inoculation, frozen, and tested in a batch run (n = 22). Samples were tested by flow cytometric crossmatch for alloantibody with 2-fold serial dilution from neat to 1:640 using BALB/c splenocytes as targets. The sum of the median fluorescence intensity of the tested sample was calculated after subtracting that of an autologous serum control. Elderly mice (ELD; 42-103 weeks) at inoculation were compared with younger mice (YOU; 11-15 weeks). Statistical analysis was performed with 2-sample t test. RESULTS: Mean age (weeks) between the groups was significantly different (ELD 69.3 ± 9.6 vs YOU 13.4 ± 1.4; P < .001). There was no difference in alloantibody between groups at baseline (ELD 0.7 ± 3.1 vs YOU 0.6 ± 0.4; P = .93). There was a higher alloantibody response at 1 month for YOU (52.9 ± 31.78) compared with ELD (5.12 ± 8.18). There was a greater difference after the 2 month (YOU 109.38 ± 66.43 vs ELD 21.97 ± 27.14; P < .0024). CONCLUSIONS: There was a difference in response to new alloantigen in this animal model. Older animals had significantly decreased responses to new alloantigen stimulation 1 month after inoculation and even more profound decreases at 2 months compared with young animals. This model may be used to study differences in immune refractoriness to antigen signaling. It may be important to adapt clinical immunosuppression in the aged population to possible decreased responses to immune stimulation.

In vitro monitoring of in vivo development of human anti-thymoglobulin antibodies by ELISA.

Thymoglobulin (rATG), polyclonal immunoglobulin, is prepared from rabbits immunized with human thymocytes. It is effective in prevention and treatment of renal allograft rejection. Human antibodies against antilymphocyte preparations can reduce efficacy by accelerating drug clearance or by inducing serum sickness. We developed an enzyme-linked immunosorbent assay (ELISA) to study posttreatment development of anti-rATG. In an Institutional Review Board-approved trial, we tested 101 allograft recipients for anti-rATG antibodies. Patients received rATG intravenously at 1.25 to 2.0 mg/kg/d for 2 to 14 days. Serum samples were obtained pretreatment and at weeks 1, 2, 4, 6, and months 3 and 6 post-rATG. ELISA plates were coated with rATG (10 microg/mL). Samples were diluted 1:100 and tested in quadruplicate. Positive samples were titrated. Horseradish peroxidase-conjugated (HRPO) affinity-purified goat anti-human immunoglobulin G (H&L) antibody reacted with bound human antibody. A chromagenic substrate for HRPO was added and optical density (OD, 490 nm) was read. An OD of twice the negative control was considered positive. Mean ODs of negative and positive controls were 0.113 +/- 0.030 and 1.042 +/- 0.196, respectively. Ten patients had detectable anti-rATG before rATG administration (1:100). Thirty-five of 101 patients (35%) developed anti-rATG antibody. Patients showed an initial positive anti-rATG antibody from days 8 to 59 after infusion and titers from 1:100 to 1:4000. In spite of rATG's postulated anti-B-cell activity, this study confirms that rATG induces sensitization at a frequency and titer seen with other xenogeneic antilymphocyte antibodies. Formation of such antixenoantibodies can have a negative impact on treatment response and hence warrant monitoring.

Latex allergen in respirable particulate air pollution.

OBJECTIVE: Urban air samples contain numerous irregular respirable black particles, which may be airborne tire fragments. A major component of tires is natural latex. Proteins of natural latex can act as adjuvants and as antigens capable of eliciting immediate hypersensitivity, making their presence in particulate air pollution an important clinical issue. METHODS: Particulate air pollutants were collected by volumetric sampling devices and characterized by optical microscopy, chemical solubility tests, and mass spectrometry. Extracts of rubber tire fragments were tested for elutable latex antigens by antibody inhibition assays. RESULTS: Identification of latex in air samples and milled material from automobile tires was supported by mass spectrometry results and was further confirmed by physical appearance and chemical solubility studies. Competitive immunoassay confirmed the presence of extractable latex antigens from rubber tire fragments. CONCLUSIONS: Latex antigens are extractable from rubber tire fragments, which are abundant in urban air samples. Given the adjuvant and sensitizing effects of latex, these airborne particles could contribute, through direct and indirect mechanisms, to the increase in both latex sensitization and asthma. The impact of these particles should be considered in the issue of morbidity and mortality rates associated with respiratory diseases and air pollution.

Drug allergy. Best diagnostic and treatment approaches.

The problems in identifying and managing drug allergy are myriad, primarily because of the number of possible agents involved, the lack of objective diagnostic methods, and the varied signs and symptoms that may occur. Allergic reactions can be life-threatening and are avoidable in most cases. A careful and serious approach is important because the effect of medical decisions can be significant. Physicians should keep in mind that an allergic reaction to any drug can occur in any patient at any time.