Mixed agglutination of leukocytes and erythrocytes in relation to studies on leukocyte antigens.

TITl)\ (JI’ ‘FIlE antigemiic structure of leukocytes amid detectiomi of “leukoagglut inimis’ ‘ have comicermied invest igat ors in immumiology amid hematology for many years. 1 ecemitly, reports of “leukoagglut.inins” iii various pathologic comiditions have appeared in rapidly increasimig miumbers, as reviewed by Dausset..’ Various serologic techmiics have been emiiployed, both in the detectiomi of these leukocyt.e agglutinating factors and in the demonstration of leukocyte antigens. Precipitation methods have been applied to this probleni,2’ but the most widely utilized technic has involved the demiionstration of direct agglutination of leukocytes. rfhi mnet.hod has also been employed in comijumiction w’ith the absorption of leukocyte agglutimiating factors fromu sera by leukocyte suspensiomis. Various workers4t have concluded that htmmnami leukocytes possess A alid B antigens correspondimig to those of the domior’s erythrocytes, based U O the (lefliolistration of absorption of anti-A amid anti-B by leukocyte suspemisions, om’ the direct agglutinatiomi of leukocytes by amiti-A amid anti-B. A recemit report by Riis’ describes the application of a direct agglutination procedure to the problem of demonstrating leukocyte antigens. Humami leukocytes were found to chump together in amiti-A amid amiti-B sera iii accordance with the erythrocyte ABO groups of the leukocyte domiors, amid the conclusion was drawmi that the A and B antigens are presemit on the leukocytes as they are omi the erythrocytes. The anti-A amid anti-B sera used by Hiis were l)rePared from blood of group B amid group A domiors, respectively, after imnmuumiization with soluble A amid B substances. This paper describes results of experiments carried out while attemuptimig to apply Hiis’ methods of leukocyte separation amid direct agglutinatiomi to the study of the amitigenic structure of leukocytes. It has been foumid that such direct agglut.inatiomi technics, employimig suspensions of leukocytes which also comitaimi erythrocyt.es, are subject to serious misimiterpretation of results. “Agglutination” of humami amid camiine leukocytes which does not correspomid to the agglutimiation reactions of the domior’s erythrocytes has been comisist.ently demolistrated with high titer human immune type amiti-A sera amid with dog sera comitaining an immune erythrocyte iSo-alitibOdy, camiine amiti-A, respectively.* This clumnping, instead, has beemi seemi to be related not to the blood group of the leukocyte (loflor but to the presemice of erythrocytes or erythrocyte ghosts which react with the amitiseruni present. Such “leukocyte agglutinates,” as they appear to be when viewed l)y ordimiary microscopy, have been shown by phase microscopy to be