Measurement of Typhi Vi antibodies can be used to assess adaptive immunity in patients with immunodeficiency.

Vaccine-specific antibody responses are essential in the diagnosis of antibody deficiencies. Responses to Pneumovax II are used to assess the response to polysaccharide antigens, but interpretation may be complicated. Typhim Vi® , a polysaccharide vaccine for Salmonella typhoid fever, may be an additional option for assessing humoral responses in patients suspected of having an immunodeficiency. Here we report a UK multi-centre study describing the analytical and clinical performance of a Typhi Vi immunoglobulin (Ig)G enzyme-linked immunosorbent assay (ELISA) calibrated to an affinity-purified Typhi Vi IgG preparation. Intra- and interassay imprecision was low and the assay was linear, between 7·4 and 574 U/ml (slope = 0·99-1·00; R2  > 0·99); 71% of blood donors had undetectable Typhi Vi IgG antibody concentrations. Of those with antibody concentrations  > 7·4 U/ml, the concentration range was 7·7-167 U/ml. In antibody-deficient patients receiving antibody replacement therapy the median Typhi Vi IgG antibody concentrations were  < 25 U/ml. In vaccinated normal healthy volunteers, the median concentration post-vaccination was 107 U/ml (range 31-542 U/ml). Eight of eight patients (100%) had post-vaccination concentration increases of at least threefold and six of eight (75%) of at least 10-fold. In an antibody-deficient population (n = 23), only 30% had post-vaccination concentration increases of at least threefold and 10% of at least 10-fold. The antibody responses to Pneumovax II and Typhim Vi® correlated. We conclude that IgG responses to Typhim Vi® vaccination can be measured using the VaccZyme Salmonella typhi Vi IgG ELISA, and that measurement of these antibodies maybe a useful additional test to accompany Pneumovax II responses for the assessment of antibody deficiencies.

Facilitated subcutaneous immunoglobulin (fSCIg) therapy--practical considerations.

There is an increasing range of therapeutic options for primary antibody-deficient patients who require replacement immunoglobulin. These include intravenous immunoglobulin (IVIg), subcutaneous immunoglobulin (SCIg), rapid push SCIg and most recently recombinant human hyaluronidase-facilitated SCIg (fSCIg). Advantages of fSCIg include fewer needle punctures, longer infusion intervals and an improved adverse effect profile relative to IVIg. Limited real-life experience exists concerning the practical aspects of switching or starting patients on fSCIg. We describe the first 14 patients who have been treated with fSCIg at the Immunodeficiency Centre for Wales (ICW), representing more than 6 patient-years of experience. The regimen was well tolerated, with high levels of satisfaction and no increase in training requirement, including for a treatment-naive patient. Two patients discontinued fSCIg due to pain and swelling at the infusion site, and one paused therapy following post-infusion migraines. Ultrasound imaging of paired conventional and facilitated SCIg demonstrated clear differences in subcutaneous space distribution associated with a 10-fold increase in rate and volume delivery with fSCIg. Patient profiles for those choosing fSCIg fell into two main categories: those experiencing clinical problems with their current treatment and those seeking greater convenience and flexibility. When introducing fSCIg, consideration of the type and programming of infusion pump, needle gauge and length, infusion site, up-dosing schedule, home training and patient information are important, as these may differ from conventional SCIg. This paper provides guidance on practical aspects of the administration, training and outcomes to help inform decision-making for this new treatment modality.

Diversity and dynamics of the T-cell response to MBP in DR2+ve individuals.

It is generally accepted that multiple sclerosis (MS) is mediated by autoreactive T cells and that myelin basic protein (MBP) is one of the target autoantigens. The T-cell response to MBP has been analysed extensively, largely through the use of T-cell lines (TCL) and T-cell clones (TCC), and to date, three immunodominant regions (13-32, 84-103 and 144-163) have been described. However, given that TCL may represent a skewed pattern of peptide reactivity, we have developed a kinetic response assay in which the proliferation of peripheral blood mononuclear cells (PBMC) from MS patients and healthy individuals was measured directly against a panel of peptides spanning the full length of human MBP. Furthermore, PBMC from each subject were tested three times over the course of 18 months. A high proportion of MS patients exhibited a significant response to eight MBP regions (1-24, 30-54, 75-99, 90-114, 105-129, 120-144, 135-159 and 150-170). TCC were subsequently generated from MS subjects and were used to further define the epitope recognized in each case. Overall, normal individuals recognized significantly fewer peptides. In addition, we noted that the T-cell recognition of any one peptide can fluctuate, appearing at one time point, regressing, and subsequently reappearing at a later date. This study provides new insight into the recognition profile and dynamics of myelin-antigen-specific T cells in MS.

Differential responses of CD45+ve T-cell subsets to MBP in multiple sclerosis.

The proliferative response of preparations of whole PBMC populations from 20 healthy individuals and 28 multiple sclerosis (MS) patients to purified protein derivative (PPD) and myelin basic protein (MBP) was monitored in a kinetic assay over a period of up to 10 days. PPD produced a classical secondary response in both groups, the magnitude being significantly reduced in the MS cohort. The magnitude and pattern of response to MBP did not differ between the two populations. The kinetic profile characteristic of a primary response was observed in both groups. Enrichment of the CD45RO+ve and CD45RA+ve T-cell subsets in PBMC led to a secondary response to PPD in the RO+ve and primary response in the RA+ve population in both groups. The response to MBP in both RO+ve and RA+ve populations exhibited primary kinetics in both MS patients and healthy individuals. However, the use of T-cell subset enriched populations allowed a finer dissection of the response to MBP which highlighted the more active role of RO-positive cells in MS patients. The most striking difference between patients and healthy individuals occurred on day 4 of culture when a greater response to MBP occurred in the CD45RO enriched population, paralleling the response to PPD, in the majority of patients. Futhermore in 4/8 patients and only 1/8 healthy individuals the response in the RO+ve cultures was maintained at a higher level than that seen in the corresponding RA+ve cultures throughout the culture period. This data indicates that a measurable memory response to MBP exists in MS patients implying prior activation of MBP reactive T lymphocytes during the course of disease.

Expression and regulation of erythrocyte auto-antibodies in mice following immunization with rat erythrocytes.

Mice immunized with intact rat red blood cells (RBC) developed serum auto-antibodies (some of which were mouse specific) to the RBC membrane components spectrin and antigens of 100 and 81 kDa as shown by Western blotting and enzyme-linked immunosorbent assay as well as RBC surface-bound autoantibodies detected by the Coombs' test. In order to discover whether these autoantibodies were induced and controlled in similar or different ways, mice were challenged with a variety of rat and mouse RBC preparations. In addition, the ability of recipients given spleen cells from the above donors to generate autoantibody responses to intact rat RBC was measured. It was found that all the autoantibodies were induced in mice challenged with rat RBC ghosts but none following immunization with butanol-extracted rat RBC ghosts or intact mouse RBC. By contrast, mice injected with mouse RBC ghosts made autoantibodies to spectrin and to the 100-kDa band. Spleen cells from mice primed with intact rat RBC, rat RBC ghosts or butanol-extracted rat RBC ghosts curtailed Coombs' autoantibody production of recipient mice challenged with intact rat RBC. Serum from recipients of spleen cells primed with intact rat RBC or the butanol extract generally failed to react with rat or mouse spectrin or with the 81-kDa band, although antibody was detected to the rat 100-kDa band. Recipients of rat RBC ghost-primed spleen cells produced antibody to rat and mouse spectrin and to rat 100-kDa band but not to mouse 100-kDa or rat or mouse 81-kDa bands. Occasionally, suppression of antibody to the rat-specific 38-kDa band was observed in recipients of intact rat RBC-primed spleen cells. It is therefore suggested that regulation of cross-reactive and mouse-specific autoantibodies as well as rat-specific antibodies occurs in an independent, determinant-specific manner.

Non-melanotic skin cancer and solar keratoses in Victoria.

The light-exposed areas of the head and neck, forearms, and dorsum of each hand were examined in 2113 adults during a one-week study. The study was conducted in the isolated Victorian rural city of Maryborough which is situated in the northern part of the Central Highlands district. Of 2113 subjects, 49 (2.32%) had at least one skin cancer and 1202 (56.9%) had at least one solar keratosis. Histological confirmation of all skin cancers and doubtful solar keratoses was obtained. Age, skin type, and sunlight exposure were the major factors influencing the prevalence of solar keratoses and skin cancers.