Effect of factor VIII concentrate on leucocyte cytokine receptor expression in vitro: relevance to inhibitor formation and tolerance induction

Inhibitor formation in haemophilia patients receiving factor VIII (FVIII) concentrate is a serious problem requiring tolerance induction therapy. Inhibitor antibody formation is dependent on interactions between leucocyte cytokines with their corresponding receptors. To investigate this we studied the effect of FVIII on cytokine receptor expression using multiparameter flow cytometry and a whole blood stimulation assay. Upregulation of many cytokine receptors was inhibited by plasma-derived FVIII (pdFVIII) in a dose-dependent manner on T cells, B cells and monocytes although interleukin (IL)-4Ralpha and IL-7Ralpha were upregulated on T cells. The decrease in cytokine receptor upregulation on B cells in the presence of pdFVIII, may result in reduced antibody production. Inhibition of CD132 in the presence of pdFVIII may result in immune tolerance in some recipients of pdFVIII. The immunomodulatory effects of pdFVIII were dose and batch dependent, some being more inhibitory than others. The inhibitory effects of prednisolone with pdFVIII, on cytokine receptor upregulation, were additive. Cytokine receptor expression was not altered in the presence of human recombinant FVIII (rFVIII) concentrate. These findings may explain the reports of less frequent inhibitor antibody formation in some recipients of pdFVIII concentrates. The use of pdFVIII, particularly the more inhibitory batches, may be more suitable than rFVIII for tolerance induction protocols. A clinical study needs to be undertaken to determine the significance of these in vitro findings.Hodge, G. ; Saxon, B. ; Revesz, T

Abnormal immune parameters in HIV-seronegative haemophilic patients

In HIV-seronegative haemophiliac patients abnormal immune parameters have been demonstrated. In this review data on these abnormalities, their aetiology and clinical consequences are summarized and discussed. The data reviewed show abnormalities at different levels of the adaptive immune system. Most of the reported abnormalities regard lymphocyte subsets and their function, both in vivo and in vitro testing. Strong evidence has not been found for a causal relation between abnormalities and the consumption of factor VIII concentrates nor the purity of the concentrates. It seems likely that certain contaminants in the factor VIII concentrates have an inhibiting effect on lymphocytes and monocytes. Two clinical consequences of the abnormalities have been suggested: a higher susceptibility for infections and a greater risk to develop malignancies. Data on these consequences, however, are contradicting and not in agreement with the good results of long-term treatment of HIV-seronegative haemophiliac patients with factor VIII concentrates. The studies reviewed give no convincing evidence that more pure concentrates are advantageous in HIV-negative haemophiliacs