Receptor-like specificity of a Plasmodium knowlesi malarial protein that binds to Duffy antigen ligands on erythrocytes.

A 135-kD parasite protein, a minor component of the Plasmodium knowlesi malaria radiolabeled proteins released into culture supernatant at the time of merozoite release and reinvasion, specifically bound to human erythrocytes that are invaded and carry a Duffy blood group determinant (Fya or Fyb), but did not bind to human erythrocytes that are not invaded and do not carry a Duffy determinant (FyFy). Specific anti-Duffy antibodies blocked the binding of the 135-kD protein to erythrocytes carrying that specific Duffy determinant. Purified 135-kD protein bound specifically to the 35-45-kD Duffy glycoprotein on a blot of electrophoretically separated membrane proteins from Fya and Fyb erythrocytes but not from FyFy erythrocytes. Binding of the 135-kD protein was consistently greater to Fyb than to Fya both on the blot and on intact erythrocytes. The 135-kD protein also bound to rhesus erythrocytes that are Fyb and are invaded, but not to rabbit or guinea pig erythrocytes that are Duffy-negative and are not invaded. Cleavage of the Duffy determinant by pretreating Fyb human erythrocytes with chymotrypsin greatly reduced both invasion and binding of the 135-kD protein, whereas pretreating Fyb erythrocytes with trypsin had little effect on the Duffy antigen, the 135-kD protein binding, or on invasion. However, instances of invasion of other enzyme-treated erythrocytes that are Duffy-negative and do not bind the 135-kD protein suggest that alternative pathways for invasion do exist.

Falciparum malaria parasites invade erythrocytes that lack glycophorin A and B (MkMk). Strain differences indicate receptor heterogeneity and two pathways for invasion.

To determine the ligands on erythrocytes for invasion by Plasmodium falciparum, we tested invasion into MkMk erythrocytes that lack glycophorins A and B and enzyme-treated erythrocytes by parasites that differ in their requirement for erythrocyte sialic acid. The 7G8 strain invaded MkMk erythrocytes and neuraminidase-treated normal erythrocytes with greater than 50% the efficiency of normal erythrocytes. In contrast, the Camp strain invaded MkMk erythrocytes at 20% of control and neuraminidase-treated normal erythrocytes at only 1.8% of control. Invasion of MkMk erythrocytes by 7G8 parasites was unaffected by treatment with neuraminidase but was markedly reduced by treatment with trypsin. In contrast, invasion of MkMk cells by Camp parasites was markedly reduced by neuraminidase but was unaffected by trypsin. We conclude that the 7G8 and Camp strains differ in ligand requirements for invasion and that 7G8 requires a trypsin sensitive ligand distinct from glycophorins A and B.

Cold autoimmune hemolytic anemia with auto-anti-AI specificity: 51chromium survival studies.

A 65-year-old woman was found to have severe autoimmune hemolytic anemia. The patient was group A1, Rho(D) positive. The direct antiglobulin test was strongly positive with anti-C3 and negative with anti- IgG. The serum contained two distinct IgM antibodies, auto-anti-I and auto-anti-AI. Both were reactive at 22 degrees C. However, the anti-AI also was reactive in saline and in albumin at 37 degrees C. An eluate revealed anti-AI and a weak anti-I. Sequential 51Chromium survival studies were done with group OI and AI red cells. The group OI red cells survived normally (97% at 24 hours) while the group A1I red cells were removed in a "two-component" pattern characteristic of IgM complement-fixing antibodies (62% survival at one hour, 49% at 24 hours). Based on these observations, the patient was subsequently transfused without incidence with six group O units of washed red cells prior to splenectomy. Although auto-anti-AI has been previously reported, this is the first case to demonstrate the use of 51Cr survival studies to determine its clinical significance.

Red cell autoantibodies in patients with acquired immune deficiency syndrome.

Mild-to-profound anemia, thrombocytopenia, and rarely neutropenia have been observed in patients with the acquired immune deficiency syndrome (AIDS). To investigate a possible immune mechanism, blood samples from 28 hospitalized AIDS patients, four asymptomatic homosexual men, four homosexual men with the AIDS-related lymphadenopathy syndrome, 30 hospitalized patients with diseases other than AIDS, and 60 blood donors were tested for the presence of atypical red cell antibodies. Eighteen AIDS patients (64%) had anti-i, nine (32%) had autoanti-U, and 12 (43%) had a positive direct antiglobulin test. One asymptomatic homosexual man and three homosexual men with lymphadenopathy also had anti-i. In contrast, of the 30 patients with diseases other than AIDS and 60 donors, none had anti-U or a positive direct antiglobulin test. One patient with sickle cell disease had anti-i. The mean hemoglobin level of AIDS patients with anti-i or anti-U was significantly lower than the mean hemoglobin level of patients who did not have those antibodies.

Invasion of erythrocytes by Plasmodium falciparum malaria parasites: evidence for receptor heterogeneity and two receptors.

Plasmodium falciparum malaria parasites with different capabilities of invading sialic acid-deficient erythrocytes were identified. Thai-2 parasites cultured in Tn erythrocytes invaded neuraminidase-treated and Tn erythrocytes twice as efficiently as Thai-2 parasites cultured in normal erythrocytes and seven to ten times more efficiently than a cloned line of Camp parasites cultured in normal erythrocytes. All three parasite lines required sialic acid for optimal invasion, but Thai-2 parasites cultured in Tn erythrocytes invaded neuraminidase-treated erythrocytes with 45% efficiency whereas Camp parasites invaded neuraminidase-treated erythrocytes with less than 10% efficiency. P falciparum malaria parasites probably possess two receptors: one that binds to a sialic acid-dependent ligand and another that binds to a sialic acid-independent ligand. Parasites may differ in the quantity or affinity of their receptors for the sialic acid-independent ligand.

Expression of red cell antigens by K562 human leukemia cells before and after induction of hemoglobin synthesis by hemin.

We studied the red cell antigens present on K562 human leukemia cells before and after induction of hemoglobin synthesis by hemin. The fetal antigens i, IF, and IT were detected on uninduced cells. While expression of both i and IT antigens increased after hemin induction, expression of IT was closely related to fetal hemoglobin synthesis as determined in experiments in which the induction was reversed. The EnaFR, NVg, and T antigens of glycophorin A were also present on uninduced cells. In contrast, the M and Pra antigens of glycophorin A, the Kell system antigens, and the P1 antigen became detectable only after hemin induction. Antigens of other major red cell systems were not detected.

An erythrocyte Pr auto-antibody with sialoglycoprotein specificity in a patient with purine nucleoside phosphorylase deficiency.

A warm auto-antibody with specificity in the Pr blood group system was demonstrated in the serum and red cell eluate of a patient with purine nucleoside phosphorylase (NP) deficiency. The antibody reacted with all cells tested except En(a-) red cells which lack glycophorin A, the major erythrocyte sialoglycoprotein. However, anti-Ena was ruled out by absorption of the antibody with En(a-) red cells. The antibody demonstrated similar serologic characteristics to Pra antibodies, except that those previously described were inactive with protease-treated red cells, while in this case, reactivity was destroyed by papain and ficin but maintained in the presence of trypsin. Inhibition analysis with purified glycoprotein fragments localized the predominant reactive antigen on the MN sialoglycoprotein between amino acid residues 40 and 61. Serologic tests demonstrated its presence in decreased amount on at least one other erythrocyte membrane structure. The serum from another patient with NP deficiency contained an autoantibody similar to the one described here. It may be of interest to explore the association of auto-antibodies to erythrocyte sialoglycoprotein antigens in NP and other immune deficiency states.

Identification of an erythrocyte component carrying the Duffy blood group Fya antigen.

The erythrocyte component carrying the Duffy blood group antigen Fya has been identified as a 35- to 43-kilodalton protein. The protein is degraded by proteases, chymotrypsin, and Pronase, which destroy its antigenicity on intact erythrocytes. Its unusual property of aggregating on being boiled in 5 percent sodium dodecyl sulfate with 5 percent 2-mercaptoethanol distinguishes it from other erythrocyte membrane proteins described to date.

Acquisition of K:1-like antigen during terminal sepsis.

This report describes a patient whose own and transfused K:-1 red cell populations became strongly K:1 during a terminal episode of sepsis due to a group D streptococcus organism, Streptococcus faecium. Subsequent in vitro studies using normal K:-1 red cells inoculated with that organism showed that it could render the red cells agglutinable by reagents containing IgG anti-K1. In addition, disrupted S. faecium organisms rendered Jkb-negative red cells agglutinable by those reagents.

Rh mosaicism and aberrant MNSs antigen expression in a patient with chronic myelogenous leukemia.

This is, to our knowledge, the first report of combined Rh and MNSs antigen alteration in a leukemic patient. Red blood cells of a chronic myelogenous leukemia patient demonstrated mixed field reactions with anti-Rho (D) reagents in August 1980. Earlier tests indicated he was Rho (D) positive in 1967, but Rho (D) and Du negative from 1973 to 1980. Titration studies with anti-hr' (c) and anti-hr" (e) indicated depressed expression, and there was also very weak s expression. One hundred per cent of cells studied from 1967 to 1980 were Philadelphia chromosome (Ph1) positive. No abnormalities in chromosomes associated with the Rh or MNSs blood groups 1 and 4, respectively, were noted. Phenotypes from August 1980 through September 1981 revealed normalization of red blood cell antigen status with an increase of Rho (D) positive cells from 35% to 100%. Chromosomal studies in October, 1980 and June, 1981 revealed Ph1 mosaicism with 25 and 75% Ph1 negative cells, respectively. These findings suggest that normalization of previously altered red blood cell antigen expression may reflect resurgence of normal stem cell lines.

Studies on the role of red blood cell glycoproteins as receptors for invasion by Plasmodium falciparum merozoites.

The mechanism of invasion of human red blood cells by Plasmodium falciparum merozoites has been studied by several indirect methods. Red blood cells of the S+s+U+ and S-s-U- blood group phenotypes were trypsin treated and their susceptibility to invasion measured. Trypsin-treated S+s+U+ cells lack the portion of glycophorin A which bears the MN blood group determinants but possess glycophorin B, whereas trypsin-treated S-s-U- cells lack both the glycophorin A MN determinants and the glycophorin B molecule. Since the treated S-s-U- cells showed an even greater loss in susceptibility to invasion that the treated S+s+U+ cells, we conclude that glycophorin B does have a role In merozoite recognition, although it appears less important than glycophorin A. Attempts to decrease invasion by pretreatment with glycosidases were unsuccessful, except for the previously reported effect of neuraminidase. N-acetyl-D-glucosamine decreases the appearance of ring-stage parasites after in vitro reinvasion of P. falciparum. However, the persistence of intact and lysed schizont-infected cells when N-acetyl-D-glucosamine was present, several hours after disappearance of these cells from control cultures, leads us to conclude that this sugar has a deleterious effect on terminal stages of parasite maturation. It is therefore not possible to conclude that N-acetyl-D-glucosamine inhibits merozoite attachment and reinvasion specifically by competition for the receptor.

Modifications of B, I, i, and Lewisb antigens in a patient with DiGuglielmo's erythroleukemia.

Loss of red blood cell antigens has been documented in patients with acute myelocytic leukemia and includes loss of A, B, and H antigens in the ABO system as well as antigens of the Rh, MNSsU, Lewis and Ii systems. The following case represents partial loss of the B, I and Lewisb antigens in a patient with erythroleukemia. Also, the loss of the I antigen was associated with a concomitant increase in i antigen, a known but rare finding. These changes within the ABO, Ii, and Lewis systems do not appear to be coincidental, as these blood group systems share a common biochemical backbone.

HLA-compatible paternity in two "fertile eunuchs" with congenital hypogonadotropic hypogonadism and anosmia (the Kallmann syndrome).

Two men are described who fulfill the criteria for both the Kallmann and the fertile eunuch syndrome, and we report the erythrocyte and HLA phenotypes of these men and their children. There were no paternal exclusions noted in red blood cell phenotypes encompassing seven separate red cell systems. The HLA phenotypes indicate that the probability that these men were the fathers of the children was greater than 99.99%.

New data do not suggest linkage between the Xg blood group and bipolar illness.

The Xg blood group antigen (a genetic marker of a region of the X chromosome at a considerable distance from protan/deutan color blindness) was studied for linkage to bipolar manic-depressive illness. A multigenerational analytic method, taking variable penetrance into account, was used. In our series of six informative pedigrees, very close linkage could be definitively ruled out, and the likelihood of less tight linkage was consistently less than the likelihood of nonlinkage.

Incompatibility in vitro and in vivo demonstrated only with saline-suspended red cells.

An unusual IgG complement-binding antibody was observed in a 64-year-old man prior to surgery. This antibody was detectable by the indirect antiglobulin test when the red cells were suspended in saline, but not when they were suspended in acid citrate dextrose or albumin solutions. Positive reactions were obtained with the patient's own red cells and with the cells of all donors tested. In vivo chromium survival studies showed that donor cells and patient cells, when suspended in saline, had 1-hour survivals of 32 and 46%, respectively. In contrast, donor and patient cells suspended in ACD solution had 1-hour survivals of 77 and 93%, respectively. We concluded that this phenomenon may casue accelerated destruction of saline-suspended cells and should be suspected whenever in vitro incompatibility is noted with red cells suspended in saline.

The Duffy blood group phenotype in American blacks infected with Plasmodium vivax in Vietnam.

We determined blood group phenotypes of 13 blacks who were infected with Plasmodium vivax in Vietnam. All were Duffy blood group positive as compared to 40--50% Duffy positive in surveys of black blood donors in the United States. The probability that 13 of 13 were Duffy positive by chance alone was P less than 0.001. All other blood groups occurred at the expected frequency. This study is further support for the hypothesis that the Duffy negative genotype (FyFy) is the basis for resistance of blacks to P. vivax.