More than 300 antigens are recognized on the red cell surface and can be classified into 4 separate categories; these are 29 genetically determined systems, 6 collections of related antigens, and the series of lo w incidence (700 series) and high incidence
Y. Tani
Japanese Red Cross Osaka Blood Center, 2-4-43, Morinomiya Joto-ku, Osaka, 536-8505, Japan, [email protected]
(901 series) antigens [2]. Among the 29 systems (Table 1), red cells which lack XK protein on the cell surface are called McLeod phenotype. McLeod phenotype is one of the rare blood cell types, defined as those that occur at a frequency of 1:1,000 or less, and was first reported by Allen et al. in 1961 [1].
In Japan, we have screened donors for rare cell types since 1987 using monoclonal antibodies (MAbs) which we have developed. Our screening strategy for McLeod phenotype is shown in Fig. 1. We do not have good MAbs against XK protein, but Kell glycoprotein is covalently linked at Cys 72 to Cys 347 of the XK protein in the red cell membrane (Fig. 2) [8] and it is well known that Kell antigen expression is markedly reduced in the absence of normal XK protein. We screen red cells by agglutination methods in an automated system such as Olympus PK7200
Table 1 The blood group systems, the genes that encode them, and their chromosomal location (ISBT, 2004) [2]
System Chromosomal CD
No. System name symbol Gene name(s) location numbers
Table 1 The blood group systems, the genes that encode them, and their chromosomal location (ISBT, 2004) [2]
System Chromosomal CD
No. System name symbol Gene name(s) location numbers
001 |
ABO |
ABO |
ABO |
9q34.2 | |
002 |
MNS |
MNS |
GYPA, GYPB, GYPE |
4q31.21 |
CD235 |
003 |
P |
P1 |
22q11.2-qter | ||
004 |
Rh |
RH |
RHD, RHCE |
1p36.11 |
CD240 |
005 |
Lutheran |
LU |
LU |
19q13.32 |
CD239 |
006 |
Kell |
KEL |
KEL |
7q34 |
CD238 |
007 |
Lewis |
LE |
FUT3 |
19p13.3 | |
008 |
Duffy |
FY |
FY |
1q23.2 |
CD234 |
009 |
Kidd |
JK |
SLC14A1 |
18q12.3 | |
010 |
Diego |
DI |
SLC4A1 |
17q21.31 |
CD233 |
011 |
Yt |
YT |
ACHE |
7q22.1 | |
012 |
Xg |
XG |
XG, MIC2 |
Xp22.32, Yp11.3 |
CD99b |
013 |
Scianna |
SC |
ERMAP |
1p34.2 | |
014 |
Dombrock |
DO |
DO |
12p12.3 | |
015 |
Colton |
CO |
AQP1 |
7p14.3 | |
016 |
Landsteiner-Wiener |
LW |
ICAM4 |
19p13.2 |
CD242 |
017 |
Chido/Rodgers |
CH/RG |
6p21.3 | ||
018 |
Hh |
H |
FUT1 |
19q13.33 |
CD173 |
019 |
Kx |
XK |
XK |
Xp21.1 | |
020 |
Gerbich |
GE |
GYPC |
2q14.3 |
CD236 |
021 |
Cromer |
CROM |
DAF |
1q32.2 |
CD55 |
022 |
Knops |
KN |
CR1 |
1q32.2 |
CD35 |
023 |
Indian |
IN |
CD44 |
11p13 |
CD44 |
024 |
Ok |
OK |
BSG |
19p13.3 |
CD147 |
025 |
Raph |
RAPH |
CD151 |
11p15.5 |
CD151 |
026 |
John Milton Hagen |
JMH |
SEMA7A |
15q24.1 |
CD108 |
027 |
I |
I |
GCNT2 |
6p24.2 | |
028 |
Globoside |
GLOB |
B3GALT3 |
3q26.1 | |
029 |
GIL |
GIL |
AQP3 |
9p13.3 |
Kell antigen testing on the Olympus PK7200 or Toraymac GR
^ using monoclonal anti-k, anti-Ku or anti-K14 by Bromelin
Weak or Negative i
Retest for indirect antiglobulin test with polyclonal and other monoclonal anti-Kell
Weak Negative
McLeod or Kmod Ko
Flow cytometric analysis !
Scanning electron microscopy ;
Indirect antiglobulin test with anti-Kx !
XK gene analysis ;
Fig. 1 Flow chart of screening of red cells for McLeod phenotype
or Toraymac GR using anti-Kell MAbs (anti-k, anti-Ku and anti-K14 etc.). In the western regions of Japan from 1987 to 2005, a total of 16,160,714 donations of red blood cells (including repeat donors) were screened using mouse monoclonal anti-k (OSK5), anti-Ku (OSK32) and anti-K14 (OSK25).
We found 182 cell donations with McLeod phenotype or Kmod and 286 with Ko. Kmod red cells express Kell antigens weakly, and Ko express no Kell antigens. XK protein expression is intact or even increased in these two phenotypes as opposed to the McLeod phenotype. To identify McLeod phenotype after screening, we examine the expression level of Kell antigens by flow cytometry (Fig. 3); cell morphology (acanthocytes) by scanning electron microscopy (Fig. 4); serum creatine phosphokinase (CPK) and haptoglobin (Hp); red cells of family members (especially mothers), and the XK gene.
Although we have not examined all 182 donors, we have identified 3 donors with McLeod phenotype (2 subsequently developed McLeod syndrome [13, 16], 2 with McLeod-like phenotype (McLeod-like red cells show the same serological reactions and acanthocytes as McLeod except they weakly react with anti-Kx) [10], and more than 50 with Kmod. Nine donors are currently registered as McLeod phenotype in the whole of Japan [3, 11, 14]. Their CPK is usually high and Hp usually low (Table 2). Of note, one donor (M-1) developed McLeod syndrome 15 years after we identified him, although his CPK was within the normal range at initial screening.
Red cells |
Fluorescence/cell |
Ko |
4.5 |
Normal |
156.0 |
McLeod |
12.9 |
Mother |
55.6 two peaks |
Fig. 3 Kell antigen expression in McLeod male, female carrier (his mother) and Ko donors. Flow cytometry using anti-Kpb (OSK36) shows that Kell antigens are weak on red blood cells from the McLeod male and that the female carrier has a mixed population (two peaks) because XK is subject to X-chromosome inactivation
Fig. 3 Kell antigen expression in McLeod male, female carrier (his mother) and Ko donors. Flow cytometry using anti-Kpb (OSK36) shows that Kell antigens are weak on red blood cells from the McLeod male and that the female carrier has a mixed population (two peaks) because XK is subject to X-chromosome inactivation
Noun alConüDl
Fig. 4 Scanning electron micrographs of acanthocytes in McLeod male and female carrier (mother). A lower percentage of acanthocytes is observed in the female carrier (JSM-5410, x1,500)
Noun alConüDl
Fig. 4 Scanning electron micrographs of acanthocytes in McLeod male and female carrier (mother). A lower percentage of acanthocytes is observed in the female carrier (JSM-5410, x1,500)
Table 2 CPK and haptoglobin |
in McLeod phenotype donors | |||
Age detected | ||||
Donor No. |
(report) |
CPK (U/L) |
Hp (mg/dL) |
References |
McLeod M-1a |
21 (1989) |
56 |
n.t. |
[13, 15] |
M-2 |
45 (1994) |
921 |
<10 |
[3] |
M-3 |
31 (1995) |
683 |
<10 |
[11] |
M-4 |
29 (1995) |
692 |
51 |
[14] |
M-5 |
34 (2000) |
1,937 |
<10 |
[14] |
M-6 |
20 (2000) |
282 |
152 |
[14] |
M-7 |
27 (2000) |
439 |
<10 |
[14] |
M-8 |
? (2000) |
862 |
<10 |
[14] |
McLeod-likeb M-9 |
21 (1989) |
382 |
<11.5 |
[10] |
Normal |
57-197 |
41-341 |
CPK creatine phosphokinase, Hp haptoglobin a Developed McLeod syndrome at 36 years old b McLeod-like: the same laboratory findings as McLeod apart from weak reaction with anti-Kx
Antigen expression |
RBC |
Possible antibodies | |||
Kell |
Kxa |
Morphology |
Produced |
CPK | |
Normal Kell |
N |
N |
N |
N |
N |
Ko (Kell null) |
(-) |
Increased |
N or elliptocyte |
Anti-Ku |
N |
Kmod |
Reduced |
Increased |
N |
Anti-Ku-like |
N |
McLeod syndrome |
Reduced |
(-) |
Acanthocyte |
Anti-Kx, Km |
N or High |
McLeod carriers |
Reduced to Nb |
(-) to N |
Acanthocyte |
N |
? |
Chorea-acanthocytosis |
N |
N |
Acanthocyte |
N |
High |
Chorea |
N |
N |
N |
N |
High |
(non-acanthocytic) |
CPK creatine phosphokinase, N normal a Anti-Kx + Km kindly gifted by Marion Reid, New York Blood Center b Flow cytometry: two peaks
CPK creatine phosphokinase, N normal a Anti-Kx + Km kindly gifted by Marion Reid, New York Blood Center b Flow cytometry: two peaks
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