J. Neppert

Inhibition of immune phagocytosis by human sera with HLA A, B, C and DR but not with DQ or EM type reactivity

Abstract. 613 sera from pregnant women were investigated for inhibition of immune phagocytosis (IPI) by monocytes exposed to anti‐D (Rh)‐sensitized human red blood cells. IPI was detected in 42 (26%) of 165 and in 78 (17%) of 448 sera assessed against monocytes from 15 or 5 panel donors, respectively. All IPI‐positive sera reacted in an allotypic pattern. Eight IPI‐positive sera tested with autologous monocytes were found to be nonreactive. Upon comparative analysis of 448 sera, a significant correlation was found between the specific patterns of IPI and lymphocytotoxicity by HLA antibodies. In addition, 13 sera (4%) were positive for IPI, but not for lymphocytotoxicity. Twenty IPI‐positive sera were tested by indirect immunofluorescence against platelets and T lymphocytes and revealed IgG antibodies in 16 and 11 sera, respectively. IPI activity could be removed from 8 out of 10 positive sera by platelet pool absorption. While virtually all sera exhibiting HLA, A, B or C‐like activity (cytotoxicity with all cells) or HLA DR‐like activity (exclusive cytotoxicity with B lymphocytes and monocytes) were IPI‐positive, IPI was infrequently observed with sera containing HLA DQ‐like activity (cytotoxicity with B lymphocytes only). IPI was also rarely seen with sera cytotoxic only to monocytes and not at all with sera containing antibodies against endothelial/monocyte antigens. We conclude that IPI is caused by cytotoxic as well as noncytotoxic HLA A, B, C, DR‐specific antibodies. This effect may bear significance for the maternal immune response against fetal antigens and may be useful for pretransplant histocompatibility testing.

Detection of antibodies specific for HLA-A,B,C,DR,DQ and DP by the erythrocyte antibody rosette inhibition (EAI) and immune phagocytosis inhibition (IPI) tests.

Two methods for the detection of murine monoclonal antibodies against determinants of the human major histocompatibility complex (MHC) were evaluated. These methods are based upon the function of Fc receptors; the erythrocyte antibody rosette inhibition test (EAI test) using B-lymphocytes and the immune phagocytosis inhibition test (IPI test) using monocytes. Compared to the EAI test the IPI test was technically easier and gave better discrimination between positive and negative results. The inhibition by antibodies of monomorphic class II MHC or polymorphic HLA-DR antigens was stronger in the IPI than in the EAI test. Antibodies against HLA-DQ and DP antigens evoked inhibition only using the EAI test. Using IgG derived from placenta in different dilutions the detection of its anti-HLA antibodies was more readily achieved in the IPI test than in the EAI test.

Reduced Immune Phagocytosis of Monocytes from Neonates Whose Mothers Produce HLA Antibodies

Abstract. In vivo immune phagocytosis of neonatal monocytes was significantly correlated to the extent of maternal HLA immunization. Monocytes from all 15 neonates of mothers with HLA antibodies show reduced immune phagocytosis. In contrast, this holds true for monocytes from only 6 out of 13 neonates of mothers without detectable HLA antibodies. We infer the hypothesis that maternal HLA antibodies bind to mononuclear phagocytes of the fetus and of the fetal part of the placenta and thus cause inhibition of immune phagocytosis. Thereby, activation and secondary cell or tissue injury will not ensue and rejection of the fetal allograft is prevented in those pregnancies in which maternal alloimmunization occurs.

Rhesus-Du and -D Incompatibility in the Newborn without Haemolytic Disease: Inhibition of Immune Phagocytosis?

We would like to comment on the interesting articles by Dias et al. [ 11 and PCrez et al. [2]. Benign courses in infants born with a positive direct antiglobulin test (DAT) due to anti-D of the mother are not only found among infants presenting with DU but also among those with normal D antigen (40% of the DAT-positive infants [3]). It is noteworthy that the inadvertent injection of 150-300 pg anti-D-IgG to D-positive infants produces only a very mild haemolytic syndrome (. . .) as a rule [4]. Two questions can be inferred: (1) Do all infants with a positive DAT due to a maternal or inadvertently administered anti-D and without marked disease exhibit a depressed monocyte or macrophage function? (2) Why is the monocyte or macrophage function depressed in some infants? In order to be able to answer the first question, studies are now in progress. We assume that there are quite a few cases among all newborns. To answer the second question, we suggest that in these cases, the maternal serum should be investigated for the presence of cytotoxic or non-cytotoxic HLA antibodies which are reactive with the infants HLA antigens. We have recently found that after the binding of these antibodies to monocytes or macrophages, their immune phagocytosis is completely abrogated, whereas other functions are well preserved [5-71. We believe that this observation, which we call the HLA antibody-induced immune phagocytosis inhibition (IPI), in vitro corresponds to the depressed monocyte or macrophage function reported by PCrez et al. [2], and in vivo corresponds to the decrease of the extravascular haemolysis. By the same mechanism, IPI apparently affects the mononuclear phagocyte system and thus ameliorates the expected haemolysis when inhibitory HLA antibodies in commercial pooled anti-D-IgG [6] is inadvertently given to D-positive infants or to D-negative recipients of transfused D-positive blood units in order to prevent immunization.

Alloantiserum Recognizing a DQw2 Split Which Is Associated with DR3

Abstract. A typing serum MUE 38539 II, was found to recognize a DR3‐associated split of DQw2. In cytotoxicity tests, MUE 38539 II yielded positive test results with B lymphocytes but not with monocytes of DR3‐positive cell donors. This was in contrast to other typing reagents for DR3 that react with B lymphocytes as well as monocytes. Lymphocytotoxicity tests using MUE 38539 II were negative with DR7‐ and DQw2‐positive cells. The assumption that the serum recognizes a DR3‐associated split of DQw2, and not DR3 itself, was confirmed by the lack of reactivity with a DQw4‐ and DR3‐positive lymphoblastoid cell line (RSH). The assumption was also corroborated using reagents from a family in which DR3 and DQw2 were not found in the usually described linkage. In two lines, DR3 was associated with DQw‐ (2707 and 2710), and in the cell line 2704, DQw2 was associated with DRw‐. The serum MUE 38539 II was exclusively cytotoxic with lymphoblastoid cell lines from those family members who were positive for DQw2, independently of the DR3 antigens of the cells.

Immunologische Untersuchungen zur Ursache des habituellen Abortes@@@Influence of immunization with allogeneic spleen cells on the rate of viable neonates in mice

SummaryFemale CBA/J (H-2k) mice mated with male DBA/2J (H-2d) mice show a high level of fetal resorption which can be reduced by immunization with BALB/c (H-2d) spleen cells. The morphologically defined fetal resorption rate upon which evaluation of the outcome of pregnancy has been based in this strain combination recently, is not equivalent to the rate of viable neonates.

Immunologische Untersuchungen zur Ursache des habituellen Abortes

Female CBA/J (H-2k) mice mated with male DBA/2J (H-2d) mice show a high level of fetal resorption which can be reduced by immunization with BALB/c (H-2d) spleen cells. The morphologically defined fetal resorption rate upon which evaluation of the outcome of pregnancy has been based in this strain combination recently, is not equivalent to the rate of viable neonates.