454 
HEMATOLOGY 
routine tests, and therefore fell into the J« 
class. Still, however, obvious exceptions to any 
"threshold hypothesis" were noted. Two-thirds 
of the cattle within the threshold range were 
type J<^^ and one-third were type J^ Fourteen 
percent of the cattle serum J concentrations 
above 34 units had erythrocytes which reacted 
not at all or only very slightly with anti-J anti- 
sera. These cells were classified as or weak 
J<^^ Fourteen percent of cattle with serum J 
concentrations below 24 units were strongly re- 
active with anti-J antisera and were classed as 
strong J". Pedigree studies suggested that 
each of the exceptional phenotjT)es was inher- 
ited. 
In another series of experiments PateP^-^'^ 
incubated washed cattle erythrocytes of all 
types in sera from J% J<=^ (strong), and J<=^ 
(weak) cattle. Red cells incubated in serum 
even when J was of high concentration, did not 
adsorb J substance. Likewise, red cells incu- 
bated in J<=« (weak) serum did not adsorb J 
substance even though in some cases the serum 
J concentration was higher than that seen in 
some J<=^ (strong) sera. However, all J« and 
J"^ (weak) cells incubated in sera from J"^ 
(strong) cattle acquired J substance even in 
those exceptional cases where the serum concen- 
tration of J was below threshold. 
In still another study J'' cells were incubated 
in serum containing 40 units of J substance 
from J<=^ (weak) cattle. The j"^ cells remained 
J negative. However, when the same cells were 
incubated in serum containing 40 units of J 
substance from J-^^ (strong) cattle, J substance 
was adsorbed and the cells became J positive. 
Thus there appears to be a serum factor which 
inhibits the adsorption of J substance on to the 
erythrocytes. During the immediate post-natal 
period, the erythrocytes of all calves are J nega- 
tive regardless of genotype. The cells of J'=^ cat- 
tle adsorb J substance from the serum and at- 
tain adult levels by the fourth week of life. If, 
however, red cells are removed from a newborn 
calf of any genotype and are incubated in sera 
from adult J'^^ cattle, they adsorb J substance 
and become J positive. 
In summary both the serum concentration of 
J substance and a heritable serum factor seem 
to play important roles in determining whether 
or not red cells adsorb J substance from the 
serum. The characteristics of the serum-anti- 
gen-cell relationship are still under investiga- 
tion. 
The biochemical nature of the soluble J anti- 
gen is currently being studied. When J positive 
bovine serum is fractionated, the total lipid 
fraction retains haptenic activity in the homolo- 
gous J system. In contrast the total serum lipid 
fraction from J negative cattle contains no J 
haptenic activity. After further fractionation | 
procedures the J haptenic activity remains only j 
in the purified glycosphingolipid^^ fraction j 
leading to the current assumption that in the j 
serum soluble form J substance is a lipoprotein ' 
with a glycosphingolipid haptenic component. | 
When low density lipoproteins are isolated from | 
bovine serum by ultracentrifugation, they are j 
found to contain J substance. In other species j 
serum soluble blood antigenic substances such 
as the Lewis blood group is humans and the A | 
blood group in pigs have been shown to contain ! 
important lipid components. | 
In 1958 Sprague^*' discovered another serum j 
soluble substance, Oc, and demonstrated that it i 
is probably an allele of the J system. Oc was i 
first detected when it was observed that sera | 
from certain J positive or J negative sheep in- | 
hibited the hemolysis of type 0 sheep erythro- i 
cytes by antisheep -0- antisera. Also, it was \ 
noted that the red cells from cattle with Oc pos- | 
itive serum, although they were not hemolyzed | 
by antisheep -O- antisera, adsorbed antisheep-0 { 
and prevented the hemolysis of type 0 sheep i 
cells by antisheep 0 in the presence of comple- 
ment. The four major defined phenotjT)es of the 
J system then are: J, JOc, Oc, and " — ". It is 
certain that many more alleles as yet undefined ' 
are also included in the J system and account i 
for the varying distribution and concentrations j 
of bovine J substance. 
The A, C, F-V, L, M, N, S, Z, and Ri - | 
systems have all been discovered by isoimmuni- 
zation techniques. There are more than 2 X f 
10^2 possible phenotypic combinations of alleles i 
which determine bovine blood types, and the 
complexity of the system will increase as more 
alleles and possibly more major blood groups 
are discovered. • 
From a practical point of view, our knowl- 
