Photosensitivity in systemic lupus erythematosus: laboratory testing of ARA/ACR definition

OBJECTIVE

The aim of our study was to evaluate the prevalence of photosensitivity in SLE as defined by either clinical or laboratory assessment, the concordance of findings obtained by two methods, and the relationship between photosensitivity and clinical and immunological parameters.

METHODS

Forty-four SLE patients and 31 healthy subjects were included. Patients and controls underwent a standard questionnaire testing and the minimal erythemal dose (MED) measurement performed by Dermalight-Blue Point. The standard questionnaire was designed in order to meet, as near as possible, the definition of photosensitivity included in the ARA/ACR criteria for classification of SLE.

RESULTS

The prevalence of photosensitivity was (patients vs controls): 57% vs 45% according to questionnaire; 79.5% vs 51.6% (P = 0.02) according to MED. The agreement between questionnaire and phototest was absent in SLE (kappa 0.01) and poor in controls (kappa 0.36). Discoid rash was significantly associated with questionnaire positive (P = 0.01) and renal involvement with questionnaire negative results (P = 0.02), serositis with MED abnormality (P = 0.03), malar rash and anti-Sm antibody with MED normal values (P = 0.03 and P = 0.01), respectively). Moreover, by multivariate analysis, malar rash and anti-Sm antibody significantly predicted MED-defined photosensitivity, with probability ranging from 42% (presence of both) to 92% (lack of both).

CONCLUSIONS

Photosensitivity is frequently observed in SLE patients as well as in healthy subjects. Its prevalence is significantly higher in SLE than in controls only when it is detected using the laboratory method. However, due to the difficulty in objectively defining such manifestation, the disagreement between questionnaire and MED results was high and its clinical meaning appears ambiguous. Thus, the use of photosensitivity as a classification criterion for SLE remains questionable, at least when it is assessed according to the ARA/ACR definition.

Mixed-type auto-immune haemolytic anaemia in a patient with HIV infection

A young HIV-infected patient presented with a severe auto-immune haemolytic anaemia with both warm and cold auto-antibodies, an infrequent category of anti-erythrocyte auto-immunity. Serological findings were compatible with the presence of a low-titre, high-thermal-amplitude anti-I cold-reacting antibody and a pan-reactive warm-reactive auto-antibody. Immunochemical characterisation of the warm antibody failed to identify any membrane protein acting as auto-antigen. This is, to our knowledge, the first reported case of mixed-type auto-immune haemolytic anaemia in a patient with HIV infection. Overt haemolysis is a very rare complication in HIV-infected patients, despite the high prevalence of a positive direct antiglobulin test reported in these patients. This suggests that HIV infection is a condition in which anti-erythrocyte auto-immunity is a serological finding without haemolytic effects in the large majority of cases.

In vitro proteolysis of the red cell membrane in patients with HIV infection

It has been suggested that acquired abnormalities of the red cell membrane due to various injuries [azidothymidine (AZT) therapy, immunoglobulin coating of red cells, differentiation abnormalities of erythroid precursors] contribute to the onset of anaemia in HIV-infected patients. In vitro proteolysis of erythrocyte membrane proteins is regarded as a molecular marker of membrane damage induced in vivo by different agents. We therefore investigated in vitro proteolysis of ghosts derived from red blood cells of 30 HIV-infected patients. Considered collectively, there was no significant increase in in vitro proteolysis in ghosts from anaemic HIV patients. However, a significantly higher degree of in vitro self-digestion of RBC membrane proteins was evident in HIV-infected patients with spleen enlargement, but not in splenomegalic patients suffering from liver cirrhosis. Neither AZT therapy nor the presence of a positive direct antiglobulin test seemed to be directly associated with increased in vitro protein breakdown. The results seem to suggest damage of the red cell membrane in HIV infection, induced by injuries on red cells during their prolonged retention inside an enlarged spleen, while it seems unlikely that AZT therapy or immunoglobulin coating of red cells play major roles in red cell damage.

Immunochemical studies on red cell auto antigens: use and limits of immunoprecipitation from biotinylated erythrocyte membrane

Erythrocyte surface was labelled by means of biotin; immunoprecipitation technique was then used to localise antigens recognised on red cell membrane proteins by: a) autoantibodies from 13 patients with antierythrocyte autoimmunity; b) commercially available anti-D and anti-k (Cellano) antierythrocyte alloantibodies. Results with alloantibodies are comparable to those obtained using radiochemical probes. Immunoprecipitations with autoantibody containing eluates showed reactivity at different molecular weights (the most common at 34-50 kD, others at 100 and 45 kD and a newly described one at 80 kD), thus confirming that many membrane proteins may act as target antigens for erythrocyte autoimmunity. We found a higher percentage of reactive immunoprecipitates than previously reported using the same labelling method. However, critical conditions to allow valuable results seem to be a threshold amount of autoantibody to precipitate any recognisable band and the sensitivity of the detection method. Hence methodological variables must be taken into consideration before concluding that "non protein" antigens trigger the autoimmune process.

Mild balanoposthitis

AIM

To identify and study cases of mild balanoposthitis (MBP) with penile pathology among patients observed at a dermatology clinic over an 18-month period.

MATERIALS

The study included 321 patients with penile pathology. The term MBP was used to describe balanoposthitis of a localised, inflammatory nature with few, non-specific symptoms and a tendency to become chronic or recur. Two hundred and seventy had diseases clearly identifiable by clinical examination or laboratory tests; 51 cases were diagnosed as MBP and these patients had blood tests (to evaluate immune status) and microbiological examination; when these proved negative, a series of patch tests was also used.

RESULTS

Of the 51 patients diagnosed as having MBP, the cause was ascertained in 34 cases (infection, mechanical trauma, contact irritation, contact allergy, etc.), whereas no specific aetiological factor was detected to explain the symptoms in the remaining 17 cases.

Clinical significance of positive direct antiglobulin test in patients with HIV infection

A direct antiglobulin test (DAT) was performed in 70 patients with anti-HIV antibodies (group A: seropositive patients without or with minimal disease and group B: AIDS patients with or without malignancies). A positive DAT was found in 24 of 70 patients (34%, significantly higher compared to 0.1% in healthy controls) and a higher prevalence of positive DAT was observed in group B than in group A patients (55% versus 21% p < 0.01). When comparing DAT-positive and negative patients within the same clinical group, no significant difference is seen in haemoglobin levels. There is no difference in serum bilirubin, haptoglobin or reticulocyte count between DAT-positive and negative patients altogether or in the same clinical group. AZT therapy seems to exert no significant influence on the onset of a positive DAT. The results confirm a high prevalence of positive DAT in patients with HIV antibodies, mainly in worse clinical conditions, and suggest that a positive DAT might be a prognostic factor in the clinical course of the disease.