Quantitation of Soluble HLA Class I Antigen in Human Albumin and Immunoglobulin Preparations for Intravenous Use by Solid-Phase Immunoassay

Abstract

Soluble HLA class I antigens in human plasma preparations possibly play a role in HLA sensitization and modulation of the immune response. We therefore have determined their concentration in albumin and immunoglobulin preparations from several commercial sources and compared these values to the concentration in normal human sera. For this purpose we used a newly developed solid-phase enzyme immunoassay employing rabbit anti-mouse antibody, monomorphic HLA class I monoclonal antibody and a polyclonal enzyme-linked β(2)-microglobulin-specific antiserum. Soluble HLA antigen concentration in 14 albumin batches from 6 manufacturers and in 16 immunoglobulin batches from 11 manufacturers ranged from 0 to 9.6 and from 0 to 20.9ng/ml. The concentration in normal human sera 1,328 ± 954 ng/ml (n = 54). We conclude that the concentration of soluble HLA concentration in albumin and immunoglobulin preparations is more than 50 times lower than in normal human serum, but considerable differences exist between products of various manufacturers.

In vitro immunosuppressive activity of soluble HLA class I and Fas ligand molecules:do they play a role in autologous blood transfusion?

“…Our findings are also in agreement with published literature data indicating that functional, soluble molecules are detectable in other blood derivatives such as albumin, immunoglobulin, and clotting factor preparations. [22][23][24][25] We suggest that most of the functional sHLA-I and sFasL molecules detectable in stored autologous blood components derive from residual WBCs that undergo membrane damage during storage. [52][53][54][55][56] This hypothesis is supported by the following findings: the greatest amounts of sHLA-I and sFasL molecules have been detected in non-WBC-reduced RBC units stored for up to 30 days, and supernatants from WBC-reduced RBC units stored for 30 days did not exert any in vitro immunomodulatory effect.…”

“…21 Large amounts of sHLA-I and sHLA-II molecules have been detected in commercial albumin, immunoglobulin, and hemostatic preparations. [22][23][24][25] In vitro studies indicate that soluble HLA molecules may modulate immunocompetent cell function in at least three ways: 1) sHLA-I molecules may bind their physiologic ligands and inhibit T-cell function by receptor blockade 26 ; 2) sHLA-I and sHLA-II molecules can be phagocytosed by antigen-presenting cells, degraded to peptides, and presented to CD4+ T cells in the context of membrane HLA class II antigens, a process known as indirect presentation and which may lead to either immune tolerance or activation 27 ; and 3) sHLA-I may induce soluble Fas ligand (FasL) expression and secretion in activated CD8+ T cells and induce their apoptosis. [28][29][30][31][32] FasL is a type II membrane protein predominantly expressed in activated T cells and neutrophils, as well as in the stroma cells of the retina and in Sertoli's cells in the testis.…”

Intravenous gammaglobulin: pharmacology, clinical uses and mechanisms of action

“…Preparations of gammaglobulin must be free of vasoactive amines such as prekallikrein activator (PKA), proteases, and pyrogens (38) and should have low titers of isoagglutinins. However, in addition to traces of albumin and IgA, IVIG preparations may contain HLA class I and class I1 antigens (39,40) or microaggregates of idiotype-anti-idiotype dimers (41). It is not know what effect these might have, but they could be important with regard to the immunomodulating effects of IVIG.…”