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Antibodies against the P1 antigen of the P blood group system have been found in 34% of P2 pigeon breeders' sera and in only 6% of the control group. In pigeon breeders, this anti-P1 activity correlates with immunization to pigeon serum and can consistently be removed by absorption with pigeon erythrocytes, serum or droppings. It is concluded that P1 or a related antigen is present in the pigeon blood and droppings and that heavy exposure to pigeon dust, as may occur in pigeon breeders, is one of the factors capable of inducing IgM antibodies to P1 antigen. The clinical importance of this finding remains to be defined. [ABSTRACT FROM AUTHOR]

The presence of anti-HL-A antibodies in a polytransfused person very often is a sign of a bad prognosis for survival of renal grafts or for the efficacity of leucocyte transfusion. In this paper, we describe the immunization of 5 patients who have been studied for several years. The number of units transfused as well as antigenic HL-A composition of these units are known for each patient. This enabled us to identify for each antigen, the number of blood units transfused (results given in %). Our observations confirm facts already described by several authors, study of voluntary programmed immunization, with the cells from the same donor. Furthermore, we are aware that there does not appear to be any direct relationship between proportion (absolute value) of the antigens received and specificity of antibodies. The time needed for an individual to become immunized does not appear to be related to the number of transfusions. This could lead to the modification of the criteria allowing to classify individuals as "responders" or "non-responders".

Antibodies against the P1 antigen of the P blood group system have been found in 34% of P2 pigeon breeders' sera and in only 6% of the control group. In pigeon breeders, this anti-P1 activity correlates with immunization to pigeon serum and can consistently be removed by absorption with pigeon erythrocytes, serum or droppings. It is concluded that P1 or a related antigen is present in the pigeon blood and drop-pings and that heavy exposure to pigeon dust, as may occur in pigeon breeders, is one of the factors capable of inducing IgM antibodies to P1 antigen. The clinical importance of this finding remains to be defined.

A study of sera of pigeon breeders showed a higher ratio of antibodies with an anti-P1 specificity in those who show clinical signs of allergic origin. By absorption of anti-P1 antibodies it was revealed that there exist in the cells, serum and excrement of pigeons, substances with antigenic properties similar to those of human P1 antigen. Pigeon breeders, and particularly those who show clinical signs of allergy, possess also other antibodies which precipitate specific antigens of pigeon serum.

Fifteen samples of cis AB bloods belonging to six unrelated families were tested by serological and thermodynamic assay techniques. The B and H antigens of cis AB bloods differ significantly from those of trans AB bloods. Differences were found among unrelated samples, but identical results were obtained within a given family : this could mean that there had been as many mutations as there were families.

A radioimmunoassay determination of the HBs antigen subtypes is discussed, it is simple but effective technique was used in association with the use of the Austria II kit (Abbott Laboratories). This method consists of an inhibition reaction of the Austria II test, by previous incubation of the antigen to be subtyped with a monospecific antibody. With this method we were able to distinguish the y and the d antigens as well as the w1, w3, w4 determinants of hepatitis B surface antigen. We have included a frequency table of the various HBs subtypes found among donor and patient populations in Liège.

A very useful index for the validation of family relationship by means of genetic markers is the proportion of males in the population whose phenotype makes paternity of a child of known phenotype impossible: the proportion often indicates probability of exclusion of paternity. It may be proved in the case of biallelic mendelian systems that this probility of exclusion of paternity may be modified by close relationship between the mother and father of the child or between the real father of the child and the presumptive father.

In diagnosis of paternity by means of polymorphic markers, the proportion of men excluded on the basis of the phenotypes of the mother and child is the best index for controlling information. Its expected value, the probability of exclusion of a male chosen at random with respect to a random child-mother couple, calculated from gene frequencies of every genetic system, may be modified by a close relationship between the mother, the real father, and the presumptive father. The father and even more the brother of the mother, if he is the father of the child, diminishes the probability of exclusion of an individual chosen at random in the population, and if he is falsely accused, he has a higher probability of being excluded. On the other hand, the brother of the real father chosen at random in the population has the least chance of being excluded. The two different rules of exclusion are involved in the calculations, the first one being the more reliable.

Patients receiving repeated transfusions sooner or later develop an anti-HL-A immunization. To prevent or to delay this immunization by transfusing "deleucocyted" blood appears in the long run, to be a vague hope. So, it became essential to use blood from donors typed for the HL-A system. In this study we have examined what would happen if a pool of 2,380 HL-A type donors were available for 110 recipients. Twenty five per cent of the recipients will have blood available from more than 5 donors with the same HL-A types as themselves, and 71% of them can receive blood from more than 5 donors sharing at least one antigen at each locus (and with no antigen known to be different between them).