Evaluation of two sources of soluble HL‐A antigens: platelets and serum

Abstract

Platelets and human serum have been evaluated as sources for extraction of soluble HL-A antigens. 3 M KC1 was found to efficiently solubilize HL-A antigens from platelets with a recovery ranging between 50 and 100 %. However, because of the low density of HL-A determinants on platelets, the yield of sbluble antigens is low, as only 1 mg of protein can be recovered from 1 x l o 9 platelets. Thus, while it is difficult to solubilize sufficient antigens from platelets for chemical characterization, it is possible t o use these materials for biological applications such as pretreatment of kidney recipients. Soluble HL-A antigen is present in human serum, since following extensive ultracentrifugation, it can still effectively inhibit the cytotoxic activity of HL-A alloantisera. The same HL-A specificities were found to be present in varying amounts among different donors. Partial purification of such antigens can be achieved by ion-exchange chromatography of serum on QAE-Sephadex.

Association between HLA and Red Cell Antigens

“…We confirm the finding that serum has a specific inhibiting effect on HLA haemagglutinins, and this inhibition is seen to be cross-reactive with regard to HLA-A2/A28, as the neutralizing effect of the corresponding white cells [19]. This cross-reactive effect has also been shown in inhibition experiments with cytotoxic HLA antibodies [22], The inhibiting effect ob served in our experiments is, however, weak, and not demonstrable for HLA-B8. This is also in accordance with observations made with cytotoxic antibodies [22].…”

“…This cross-reactive effect has also been shown in inhibition experiments with cytotoxic HLA antibodies [22], The inhibiting effect ob served in our experiments is, however, weak, and not demonstrable for HLA-B8. This is also in accordance with observations made with cytotoxic antibodies [22]. Thus, also in this respect, the behaviour of HLA anti gens/antibodies is different from that of the Chido and Rg antigens, especially the for mer.…”

“…A specific neutralizing effect of serum on HLA cytotoxic antibodies has been demon strated, even if this effect is weak and vari able in unconcentrated serum [22,27]. Swanson [30] has reported a similar in hibiting effect on HLA haemagglutinins, and that incubation of RBC in serum from HLA reactors may change HLA non-reac tors into reactors with HLA haemaggluti nins.…”

Enhanced representation of HL-A antigens on human lymphocytes after mitogenesis induced by phytohemagglutinin or Epstein-Barr virus.

“…PHA stimulation was also 100 6 80 -6h .2~~~~~~~~L found to induce a similar pattern in the increase of the expression of the specificities W-28, HL-A7, and HL-A27. A synchronous variation in HL-A and H-2 expression with the growth cycle of culture lymphoblasts has been reported (13,18,19), varying over a 3-fold range. PHA appears to evoke a similar cell surface change in the expression of HL-A antigens, although of larger magnitude.…”

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

“…However, application of this method requires large amounts of purified HLA antigens which are not readily available. Pellegrino et al [10,11] reported that soluble HLA class I antigens are present in serum in a functional Major histocompatibility complex (MHC) class I mol ecules (HLA-A,B,C) are heterodimeric cell surface anti gens composed of a 44-kDa highly polymorphic heavy chain and noncovalently associated 12-kDa ß2-microglobulin [1], HLA class I antigens are expressed on most nucleated cells, platelets and are also known to be present in serum in soluble form [2,3]. Recently, Krangel [4] and Dobbe et al [5] have shown that the heavy chain of this soluble class I antigen exists in differents forms with ap form and are immunogenic.…”