Recognition by Human Β Cells of Foreign Antigen
in the Context of the MHC: a Review
[ GOUIMY Α VAN LiruwtN and J J VAN ROOIJ
Department of Immunohaematology and Bloodbank, University Hospital of leiden Rijnsbuigerweg 10 2333 AA Leiden 1 he Netheilands
Ihe expenmental evidence foi the existence of human Β cells that recognize foieign antigen in the conlexl of the MHC is very restnrted not lo say limited to only one example (Van Leeuwen et al 1979) at least with legatd to the known nature of the MHC allele and the antigen mvolved On the other hand in exenmental animal modeis, the number of antigen specific MHC restricted antibodies leported (see the detailed descnptions by different authois in this volume) greatly exceeds one though it does not reach overwhelming levels Nevertheless, the independent observations strongly support the notion that MHC lestncted antibodies do exist although with Special regard to the human studies moie data aie needed to strengthen the evidence for the existence of such antibodies in man
The assumption that some Β cells aie capable of geneiatmg MHC restricted anti gen specific antibodies is based on oui earlier observation Moie than one decade has now elapsed smee participation ot the HLA molecules in the lecognition of foi eign antigen by cytotoxic T-lymphocytes (Cils) was leported (Gouimy et al 1976) Although such recognition is chaiactenstic foi Γ colls a caieful analysis of the seium of the female patient whose lymphocytes were able to demonstrate HLA A2 restricted H Υ specific cytotoxic activity levealed Β cell mediated activity compara ble with the cytotoxic Τ cell responses (Van leeuwen et al 1979) It became appai ent that lympholytic antibodies weie piesent in the serum which reacted with some mononuclear cells labend with anti Ig Ihe antibody activity was found in the IgM fraction The scrum was tested agamst a panel of iymphocytes of healthy male and female donors either positive οι negative for the lestncting molecule (i e Hl Α Α2) Ihe lesults demonstratec, that all Hl Α A2 positive male donois weie rea ting witn this antiserum whe eas the lymphocytes ol III Α Α2 negative male οι female donors were negative in the complemcnt dependent cylotoxicity assay Nevertheless of the H1A A2 positive female donois two gave a boideihne positive reaction It should be noted that ihe lymphocytes of onp of Ihe latter females weie also boideilmo lysed by the hl Α A2 lestnctod anti 11 Υ C ILs in the CV1I assay Comparalive analysis between thr outcome of the CM1 assav and the icactions obtained with the anti seium showed striking similanty (lable I) Because of the almost peifect correlation between the reactivity patterns of the CIIs and the anlibody it is ifasonable to assume that the HLA A2 testiicted antibody tecogni/es the same epitopes on the III Λ Α2 and on the 11 \ anligen as do ihe III Λ Α2 lestucted CIIs obtained fiom the same individual Since vanants exist both at the level ol the anligen
MHC +X Rpcognilion by Human Antibody V: >\ I eiden, 'p forcign only one jrc o i the al animal d (see the >eds one, ependent do exist, eeded to f ted anti-e danti-ecadanti-e on of for-al 1976) ihe serum > H1A-A2 compara-mo appat \ith some η the IgM nale and III Α Α2Ι (tmg with ile donors oss o i the It should boiflerlinp ν c analvsis ι (he und onolation easonablo epitopes - obtaincd i<> antigen
Tabie 1. Corrolation bctween the lysis patterns by the C TLs and by tho antiserum, both denved from the same individual tested against several healthy male and fomale individuals Cytotoxir act/vity
as exhibited by
Panel ceüs tested by CTI s and antibody A2+ males" in =20) A2+ females (n=7) A2— females, A2— males (n=16) 20 20 1b 2 Antibody
3 A2 + = I ILA A2 positive A2 - = Hl A-A2 negative
b Only one of the two HLA-A2+ female cells tested by both CTI s and antibody gave a bor derline positive icaction with the I l-Y spetific C FLs
Η Υ and at the level of the restncting molecule Hl A-A2, our hypothesis could be evaluated
To approach the question of whether CTls and antibody recogm/e similar struc-tures on the H-Y molecule, we studied the chromosomes and the reaction patterns of a small senes of individuals with abnormal sex chromosome constitutions (Coulmy e+ Μ 1983) It should be emphasized that the number of cases which rould be studied was limited since the reagents are applicable only to those mdividuals who carry the appropnate MHC restncting moiecule The picture that arose from the latter study confnmed the earher observed correlation between the reactivity patterns of CTLs and antibody Moreover, the combmed analysis (each showmg the same discnminatory patterns) levealed a correlation with the presence of the cyto-logically detectable Y-chromosome matenal but nol with the presence of festes So far we have assumed that the antigen recogni/ed by both the Β cells and the Γ cells is most probably identical with the classical transplantation antigen H-Y Neverthe-less, we have not yel reached the point at which we would be justified in making Statements concerning tho nature of the H-Y antigen as recognized by CTI s and antibody Current exammation oi sex reversed humans by combmed analyses of dif ferent sets of Y-DNA probes and l l-Y specific C fls will hopefully resolve this issuc (Simpson et al 1987)
lo elaborate on the assumption that IILA-A2 restncted Β cells use the same MHC epitopes as I I[A A2 restncted I cells for the recognition of the "MHC + X" complex, functional analyses of an established MHC class I "vanant" IIIA-A2 molecule were carned out foi this purpose sorological HLA-A2 positive lymphocytes from a male donor designated M7 were used Biddison et al (1980a) demonstrated, by the use of Hl Α Α2 restncted influen/a virus immune Γ cells, a lack of recognition of virus infected III Α A2 positive lymphocytes from donor M7 Additionally, biochemical analysis by means of isoeleclnc focusing of the Hl Α A2 molecule fiom donor M7 demonstrated a differenre in the III Α Α2 heavy polypeptide chain when compared with the HIA-A2 molecules of other donois (Biddison et al 1980b)
I h e lymphocytes from donor M7 were subsequenlly analy/ed in oui laboratoiy using both the HIA-A2 restncted H-Y antigen specific C fls and antibody lable 2 shows that HIA A2 restncted anti H-Y C l l s failed to lyse the lymphocytes from
36 Ε Goulmy et al
Table 2 Differential recognition of Hl Α A2 vanant cells (M7) by HLA A2 restricted Η Υ anti
gen specific CTLs and antibody
Target Cells HLA A2 restncted anti Η Υ
CTLs Antibody
HLA A 2 + male cells HLA A 2 + male cells HLA A 2 + male M7 cells HLA A 2 + female cells
64d 67 1 3 45a 41 Γ36] °/( cytotoxicity
donor M7 This reaction pattern is comparable to the absence of recognition usmg HLA A2 restncted mfluenza virus specific CTLs (Biddison et al 1980a) However the HLA A2 restncted anti Η Υ antiserum did react with the M7 cells to an extent com parable to that in other HLA A2 positive male donors it is clear from these observa tions not only that alloimmune HLA A2 specific antisera and alloimmune HLA A2 specific CTLs might use different epitope(s) on the same H I A A 2 molecule for allorecognition (Horai et al 1982) but also that monospecific anti II Υ antiserum and "monospecific anti-H Υ CTLs (both denved from the same mdividual) appar ently use different epitopes on the HLA A2 molecule for associative recognition of the foreign antigen Thus the Η Υ specific antibody recognizes seif determinants on the HLA A2 molecule that are distinct from those that are seen by Η Υ specific CTLs
Lately addilional Information has become available on the more precise location of the target structures for CTLs on the HLA A2 molecule Combined investigation (resultmg from a collaborative effort) of the HLA A2 vanant molecules at the molec ular (Ezquerra et al 1986) and at the functional (Goulmy et al 1984) level demon strated that ammo acid changes at position 43 and in the residues 145 157 (i e cellular defined subtypes HLA A2 2 and H I A A 2 3) lead to the loss of epitope(s)
necessary for associative recognition of the Η Υ antigen by HLA A2 restncted CTls Interestingly enough a Single ammo acid change at position 9 in the heavy cham of the HLA A2 molecule (ι e cellular defined subtype LILA A2 4) does not affect the tecognition of Η Υ by HLA A2 restricted CTLs
Obviously it is of interest to examine the reactivity pattems of the cells of the individuals expressmg the cellular defined HLA A2 i and HLA A2 4 subtypes (donoi M7 see Table 2 carnes fhe HLA Λ2 2 subtype) with oui Hl Α A2 restncted Η Υ spe cific antibody Unforturately the amounts of the Η Υ specific antibody at our dispos al were small the Η Υ aitibody was only present in the patient s serum for 1 yeai after bone marrow transplantation and the activity declmed theieafter
At present attempts are being made at the in vitro production of the Η Υ anti body by Epstem Garr virus transformed Β cells denved from the original Ll Υ pro ducing female patient
Acknowledgrmnf; Ihe authors vvouid like to thank Eis Blokland and Jos Pool foi thtir tcchni
cal assistance and Ingrid Cunel for typmg the manuscnpt Τ his woik was supported in pari by grants from the Dutch Foundation for Medical Health Reseaich (Medigon) which rs subsid
MHC + X Recognition by Human Antibody 37 ized by the Dutch Organization for the Advancement of Pure Research (ZWO), and the J.A.Cohen Institute for Radiopathology and Radiation Protection (IRS).
References
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