Two monoclonal antibodies detecting allotypic determinants of HLA-A

Three mouse hybridomas producing cytotoxic antibodies against HLA were established. By standard microcytotoxicity test against panels of normal controls, the antigen defined by MA-9 antibody (IgM) showed a good correlation with HLA-A9 alloantigen detected by conventional typing alloantisera (r = 1.0). Family studies also showed that MA-9 determinant segregated with HLA-A9. MA-10 antibody (IgM) reacted with all HLA-A10 positive lymphocyte donors and cross-reacted with two thirds of HLA-AW33 positive donors. Ml-1 antibody (IgG2a) reacted with all the panel cells tested and immunoprecipitated a molecule of 43,000 daltons from Nonidet P-40 lysates of 3H-glucosamine-labelled cells. The results showed that MA-9 and MA-10 antibodies can be used as routine tissue typing reagents.

Polymorphism and stability of histone gene clusters in Drosophila melanogaster cultured cells

In a previous communication (Saigo, K., Millstein, L. and Thomas, C.A., Jr. (1981) Cold Spring Harbor Symp. Quant. Biol. 45, 815-827), the overall structure of histone genes of Schneider line 2 cells was shown to extensively differ from that of Oregon-R embryo from which the cell line was established, and it was speculated that the histone genes might be reshuffled extensively during either the periods of the establishment, or maintenance of cell lines, or both. To establish the validity of this notion the structure of histone genes was examined in Drosophila melanogaster cultured cells. The overall organization of histone gene clusters was found to be stably maintained in both the periods for the establishment and maintenance of cultured cells, indicating that the previous assumption is inadequate. Instead of an extensive rearrangement, minor structural changes were found to occasionally occur probably by simple base substitutions and/or, deletion or insertion of very short DNA pieces. It was also shown that the extensive variation in structures of histone genes in cultured cells such as Schneider line 2 are attributable to polymorphism on the level of individual flies.

Monoclonal antibody against microtubule associated protein-1 produces immunofluorescent spots in the nucleus and centrosome of cultured mammalian cells

A monoclonal antibody was raised against the highest molecular weight protein associated with microtubules (MAP-1). Its specific binding to MAP-1 was determined by immunoblotting of the gel electrophoretogram of microtubule proteins prepared from porcine brain. The antibody reacted only with MAP-1, not with MAP-2, tau or tubulin. Indirect immunofluorescent staining by this antibody showed bright intranuclear spots, the centrosome and the faint meshwork of the cytoplasm in several types of cultured mammalian cells; HeLa, PtK2, human skin fibroblasts, mouse melanoma cells, Chinese hamster ovary cells. The nuclear spots in the interphase cells, were replaced by diffuse enhanced fluorescence throughout the cell except for chromosomes during mitosis. They reappeared in late telophase, first in the cytoplasm, late in the nucleus. The punctate pattern of nuclear immunofluorescence was not affected by microtubule-depolymerizing agents. The result that it persisted on residual cell structures after extraction with a high salt concentration buffer containing Triton X-100 followed by digestion with DNase I and RNase A suggests that the antigen is associated with the nuclear skeleton.

[Analysis of cell surface antigen of kidney cancer by autologous sera and monoclonal antibodies]

Sera from renal cancer patients were tested for reactivity with surface antigens of cultured autologous renal cancer cells, so called "autologous typing". Reactive sera from six patients were analyzed by absorption tests with autologous, allogeneic, and xenogeneic normal and malignant cells. The absorption analysis indicated the detection of three classes of surface antigens by autologous sera, i.e. class 1, individually distinct tumor antigens, class 2, shared tumor antigens, and class 3, normal cell surface antigens. Seventeen monoclonal antibodies derived from fusions with spleen cells of mice immunized with renal cancer cell lines, which showed the class 1 or class 2 antigens, identified nine cell surface antigenic systems. None of the mouse antibodies identified in this study was succeeded in recognizing antigens that are tumor specific. Three of antigenic systems, however, showed the specificity for renal tissue, and seemed to be useful for immunopathological diagnosis.

[Subclassification of acute leukemia and monoclonal antibodies]

Recent advances in immunological techniques, particularly, the development of monoclonal antibodies by the hybridoma technique, have contributed a great to the understanding of cell surface antigens of human hematopoietic cells. We have produced monoclonal antibodies detecting the following antigens: Ia-like (NL-12, MD-1A), Null-ALL associated (NL-1, NL-22, HL-47), T cell (ATL-27, Thy-64), myelocyte-monocyte (HL-1), and monocyte (HL-21). Using these antibodies, serological typing of leukemia was performed and it was found to facilitate considerably the diagnosis of leukemia. In consideration of therapeutic use of two antibodies detecting Null-ALL associated antigen (NL-1, NL-22), reactivity against major organs was studied by immunoperoxidase staining. NL-1 antibody was reactive with glomeli and tubules of kidney and epithelial cells of small intestine, while NL-22 antibody reacted with tubules of kidney, liver cells and some other tissues. This results suggested the difficulty of application of these antibodies directly to the patients. Reactivity against colony forming cell in bone marrow was also examined and moderate inhibition was observed by both antibodies, which might allow to eliminate ALL cells in cryopreserved autologous bone marrow cells from bone marrow transplantation patients by the treatment with appropriate concentration of antibodies.

Serological analysis of cell surface antigens of HL-60 cells before and after treatment with a phorbol ester tumor promoter

The human HL-60 cell line derived from acute promyelocytic leukemia, consisting of promyelocytic type of cells, was able to differentiate into adherent cells with monocytemacrophage features by the treatment with 12-0-tetradecanoyl phorbol-13-acetate (TPA). Cell surface antigens of HL-60 cells before and after TPA treatment were studied with monoclonal antibodies and four hybridoma clones producing IgM antibodies were established. Two antibodies (HL-21 and HL-47) reacted only with the immunizing TPA-treated HL-60 cells, and HL-1 antibody produced against untreated cells was reactive with both TPA-treated and untreated cells, but HL-5 antibody reacted predominantly with the immunizing untreated cells. Serological reactivity against various types of normal hematopoietic cells and acute leukemias (diagnosed by the French-American-British classification) was studied by immune adherence assay and immuno-electron microscopy. HL-21 antibody was reactive with monocytes and most cases of M4 and M5 types of acute non-lymphocytic leukemia cells. HL-47 antibody did not react with the cells of myelocyte-monocyte lineage or mature lymphocytes, but it did react with one-third of acute lymphocytic leukemia (L1 and L2) cases. Since all HL-47+ cases were included in the group of common ALL antigen positive cases, it was estimated that HL-47 is a differentiation antigen present on lymphocyte precursors, from which null-cell type acute lymphocytic leukemia cells generally originate. HL-1 antibody reacted with the cells of myelocyte-monocyte lineage as well as those of most acute non-lymphocytic leukemias. HL-5 antibody reacted with granulocytes and M2 type of acute myelocytic leukemia cases, and also with M5 type of acute monocytic leukemia cases. Serological studies of these antibodies revealed that TPA can induce to differentiate HL-60 cells not only into HL-21+ macrophage-like cells, but also into HL-47+ lymphoid stem cells. In addition, these antibodies were demonstrated to be very valuable for differential diagnosis of acute leukemias.

Serological analysis of cell surface antigens of null cell acute lymphocytic leukemia by mouse monoclonal antibodies

Nine antigens systems were defined. Two were related to HLA-A,B,C and to Ia-like antigens; the others could be grouped into three categories. (i) NL-22, NL-1: NL-22 antibody reacted with leukemia cells from 12 to 16 cases of null cell acute lymphocytic leukemia (null-ALL) but not with any other type of leukemia tested or with lymphoid cells of various origins. Among cultured cell lines tested, one (NALM-6) of three null-ALL cell lines was positive, the others were negative. Absorption analysis confirmed the restriction of NL-22 antigen to null-ALL. NL-1 antibody was reactive with leukemia cells from 10 to 16 cases of null-ALL and 3 of 6 cases of chronic myelocytic leukemia in blastic crisis (CML-BC). The antigen was present also on a minor population of normal lymphoid cells. The distribution and molecular weight (100,000; glycoprotein) of the NL-1 antigen resembled that of the previously described common ALL antigen (cALL). (ii) NL-30, NL-4: Both antibodies exhibited almost identical patterns of reactivities against cultured cell lines tested. They reacted with leukemia cells from some cases of null-ALL, adult T-cell leukemia, and CML-BC, although they showed discordance in their reactivities against a panel of leukemia cells, (iii) NL-9, NL-8, NL-25: These three antibodies detect serologically distinguishable determinants on a broad range of leukemias and normal lymphoid and hematopoietic cell types. The antibodies analyzed in this study provide evidence for the heterogeneity of null-ALL by demonstrating a variety of antigen phenotypes on leukemia cells. One of the antigens (NL-22) appears to be restricted to null-ALL.

[Flow cytometric analysis of cell surface antigens on leukemia cells by monoclonal antibodies and its application]

Nine monoclonal antibodies against null cell ALL cells were obtained by mouse hybridoma technique. Using two antibodies, namely B-1 and D-22, out of these, cell surface antigens on various leukemia cells, normal bone marrow cells, spleen cells and cultured cells were analysed by means of flow cytometry. B-1 antibody was found to have reactivities against null cell ALL cells as well as some CML-blastic crisis cells. The antibody reacted against some cultured lymphoid cell lines and also several percent of bone marrow cells. The reactivities of B-1 antibody were quite similar to those of c-ALL by Greaves et al and J-5 by Ritz et al. Radioimmunoprecipitation experiment suggested that B-1 antibody define the same antigen as the other two do. Meanwhile, D-22 antibody reacted against null cell ALL cells, but did not react against any other types of leukemia cells or any other cultured cell lines, or bone marrow cells. Thus D-22 antibody was considered to have higher specificity for null cell ALL cells than any other antibodies reported. On the other hand, the analyses by flow cytometry were well correlated with the analysis by immune adherence assay and by immunofluorescent microscopy. Besides, the analysis by flow cytometry provided us precise quantitative data and histogram pattern of positive cells. Furthermore, detailed examination of subpopulation could be done using cell sorter or other biological features could be analysed simultaneously using another fluorescent dye. Although, it has a few limitations, flow cytometry could take over other methods which are currently used in this field. Finally, the possibility of this method for the clinical diagnosis of leukemia was discussed.

Intermediate-density lipoprotein and cholesterol-rich very low density lipoprotein in angiographically determined coronary artery disease

The relationship between the concentrations of intermediate-density lipoprotein (IDL) and other lipoproteins and the extent of coronary artery disease (CAD) was studied in 182 consecutive patients evaluated by selective coronary cineangiography. On univariate analysis, the extent of CAD correlated significantly and positively with very low density lipoprotein (VLDL) cholesterol, IDL cholesterol and low-density lipoprotein (LDL) cholesterol, and negatively with high-density lipoprotein (HDL) cholesterol. Analysis of four subgroups divided by IDL cholesterol and LDL cholesterol levels indicated that moderately increased levels of IDL cholesterol were closely associated with a high frequency of CAD. Moreover, multi-variate regression analysis demonstrated that IDL cholesterol for men, LDL cholesterol for men and women and HDL cholesterol for men were significant variables of use in the final weighting procedure. IDL cholesterol was closely associated with cholesterol-rich VLDL. This study shows that IDL and cholesterol-rich VLDL combine to contribute to the development of CAD.

Cell surface antigens of human renal cancer defined by mouse monoclonal antibodies: identification of tissue-specific kidney glycoproteins

Seventeen monoclonal antibodies derived from fusions with spleen cells of mice immunized with established culture lines of renal cancers identified nine cell-surface antigenic systems. Six of the systems (gp160, S25, gp120r, gp120nr, gp115, and V1) represent antigens not previously described. The other three systems are related to HLA-A, -B, and -C heavy chain and A and B blood group antigens. The most restricted of the newly described antigens are gp160, S25, and gp120r. These determinants are found only on cells of renal origin, both normal and malignant, and represent differentiation antigens of human kidney. In addition to the difference in the molecular weight of two of these antigens, gp160, S25, and gp120r can be distinguished on the basis of differential expression on a panel of cultured renal cancers and normal kidney epithelium and fetal kidney cells. Glycoproteins bearing gp120r share a determinant with renal gp120nr (as indicated by sequential precipitations with monoclonal antibodies that detect gp120r and gp120nr), but gp120nr is found on a broader range of cell types, including fibroblasts and cell lines derived from lung, bladder, and colon cancers. The two other new systems, gp115 and V1, have characteristics of broadly occurring differentiation antigens but can be distinguished from each other and from gp120nr by differences in molecular weight, heat stability (V1 is a heat-stable determinant), and differential expression on cell types of diverse origin.

Effects of ML-236b (compactin) on sterol synthesis and low density lipoprotein receptor activities in fibroblasts of patients with homozygous familial hypercholesterolemia

We studied biochemical genetics of low density lipoprotein (LDL) receptor mutations in fibroblasts from six homozygous and five heterozygous patients with familial hypercholesterolemia (FH). Three of six homozygotes are receptor-negative type and the other three homozygotes are receptor-defective type. In the cells from three receptor-negative homozygotes, the receptor binding, internalization, and degradation of (125)I-LDL were 0.5+/-0.3 ng/mg protein (mean+/-SEM), 14+/-8 and 8+/-6 ng/mg protein per 6 h (four normal cells; 44+/-3, 386+/-32, and 1,335+/-214 ng/mg protein per 6 h), respectively. In the cells from three receptor-defective homozygotes, the receptor binding, internalization, and degradation of (125)I-LDL were 6+/-2, 29+/-8, and 90+/-32 ng/mg protein per 6 h, respectively. In these six homozygotes, two pairs of siblings are included. Two siblings in the same family were classified as receptor-negative and two siblings in another family were classified as receptor-defective. The receptor-negative phenotypes and the receptor-defective phenotypes bred true in individual families. The cells from five heterozygotes showed approximately 46% of the normal activities of receptor.ML-236B, competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase), completely inhibited the incorporation of [(14)C]acetate into digitonin-precipitable sterols in fibroblasts from normal subjects and heterozygous and homozygous patients with FH with the concentration of 0.5 mug/ml. However, at 0.05 mug/ml of ML-236B sterol synthesis in fibroblasts from homozygotes was not completely suppressed in contrast to normal and heterozygous cells. Moreover, after preincubation with 0.05 mug/ml of ML-236B for 24 h in medium containing lipoproteins, sterol synthesis in the cells from receptor-negative homozygote showed 75% of the initial activity compared with that of 25% without preincubation. In the cells from a normal subject and a heterozygote, sterol synthesis was inhibited even after preincubation. These results suggest that (a) the inhibitory effect of ML-236B is overcome in homozygote cells by their high intracellular levels of HMG-CoA reductase and (b) that a higher dose of ML-236B may be required to lower serum cholesterol levels in FH homozygotes than in heterozygotes.

Serum lipids, lipoprotein lipids and coronary heart disease in patients with xanthelasma palpebrarum

Serum lipids and lipoprotein lipids were studied in 53 patients (21 males and 32 females) with xanthelasma palpebrarum and 40 age-matched normal controls (20 males and 20 females). Patients were subdivided into patients with normolipidemia, hyperlipidemia or familial hypercholesterolemia (FH). In both male and female patients with hyperlipidemia or FH, the serum cholesterol (Chol) levels were significantly higher than in normal controls. In both male and female patients with normolipidemia or hyperlipidemia, the VLDL-Chol levels were significantly higher than in normal controls. Male patients with FH showed significantly higher levels of VLDL-Chol than normal controls. Both male and female patients with normolipidemia, hyperlipidemia or FH showed significantly higher levels of LDL-Chol, lower HDL-Chol levels and lower HDL-Chol/LDL-Chol ratios than normal controls. In both male and female patients with hyperlipidemia and in male patients with FH, the serum triglyceride (TG) levels were significantly higher than in normal controls. Both male and female hyperlipidemic patients showed significantly higher levels of VLDL-TG than normal controls. In male patients with FH, the VLDL-TG levels were significantly above the control levels. In male patients with normolipidermia, the LDL-TG levels were significantly higher than in normal controls. In both male and female patients with hyperlipidemia or FH, the LDL-TG levels were significantly higher than in normal controls. The HDL-TG levels in patients with normolipidemia (males) or FH (females) were significantly lower than in normal controls. The prevalence of coronary heart disease in patients with normolipidemia, hyperlipidemia or FH was 29.4%, 24.0% and 45.4%, respectively.

Comparison of [3H]glucosamine-labeled glycoproteins from human renal cancer and normal kidney epithelial cell cultures by two-dimensional polyacrylamide gel electrophoresis

Two-dimensional polyacrylamide gel electrophoresis has been used to compare the Nonidet P-40 soluble, [3H]glucosamine-labeled glycoproteins of human kidney cancer cell lines and short-term cultures of normal kidney epithelia. Two pairs of autologous combinations of tumor and normal cells and also six other cancer lines and four normal cultures were examined. Because autologous cells could be compared, possible differences due to allogeneic variations could be eliminated. The electrophoretic patterns given by tumor and normal cells were extremely similar. Nevertheless, more than 10 differences could be recognized when randomly selected combinations of cancer and normal cells were examined in detail. Of these differences, however, only one was consistently found in all possible combinations of cancer and normal cells. Cancer cells had three prominent components of molecular weight 27,500 and pIs of 5.7, 5.3, and 4.9, respectively. Normal cells have a fainter and different constellation of spots in this region, with the more acid component (pI 4.9) being absent (or barely detectable). The pattern of fetal kidney cells resembled that given by normal adult kidney.

Comparison of multiple rosetting assays for detecting antibody reactivity of different immunoglobulin classes against surface antigens of benign and malignant tissue culture cells

Four serological assays for detection of antibody reactivity against surface antigens of benign and malignant cells have been evaluated. In all four assays, antibody attached to the surface of a target cell is detected by a rosette of indicator red blood cells. Of the four assays (antibody mixed hemadsorption assay, immune adherence assay, anti-C3 mixed hemadsorption assay and protein A assay), the anti-C3 mixed hemadsorption assay showed highest sensitivity. By using purified IgM and IgG fractions we could demonstrate that, except for the protein A assay, all assays show reactivity both with IgG and IgM. Protein A assay detected only the IgG fraction, with high sensitivity. The optimization of the four assays is described and the importance of using multiple assays is emphasized.

Tumor-specific antigens

Based on autologous serological typing of cultured astrocytoma cells from 30 patients, three classes of surface antigens have been defined. Class I antigens are restricted to autologous astrocytoma cells. Class II antigens are shared by autologous as well as certain allogeneic tumors, but are not detected on normal cells. Class III antigens are not tumor-specific and are found on both normal and malignant cells. This analysis of human astrocytoma, with the recognition of three classes of surface antigens recognized by autologous sera, resembles the results of autologous typing of human malignant melanoma, acute leukemia, and renal carcinoma.

Cell surface antigens of human renal cancer defined by autologous typing

Sera from 28 patients with renal cancer were tested for reactivity with surface antigens of cultured autologous renal cancer cells. Four serological assays were used to survey sera for autologous antibody. Immune adherence, protein A, and C3-mixed hemadsorption assays detected reactivity in a high percentage of patients (80-100%), whereas mixed hemadsorption assays were negative with sera from all but one patient. Reactive sera from six patients were analyzed by absorption tests with autologous, allogeneic, and restricted to autologous renal cancer cells; class 2 antigens, present on certain allogeneic renal and nonrenal cancer cells; and class 3 antigens, found on a wide variety of normal and malignant cell types. The sera of one patient detected class 1, 2, and 3 antigens, the sera of three patients detected class 2 antigens, and the sera of two patients detected class 3 antigens. This analysis of renal cancer, with the recognition of three classes of surface antigens recognized by autologous sera, resembles the results of autologous typing of three other human malignancies: malignant melanoma, acute leukemia, and astrocytoma. Evidence provided by autologous typing of these cancers indicates that class 1 and class 2 antigens are tumor-restricted and that under certain circumstances these antigens are immunogenic for the autologous host.

Achilles tendon thickness and ischemic heart disease in familial hypercholesterolemia

Achilles tendon thickness (ATT) of 112 patients with familial hypercholesterolemia (FH) with and without ischemic heart disease (IHD) was measured radiographically and was compared with that of normal subjects. The mean and SD of serum cholesterol in the heterozygotes (107 cases), the homozygotes (5 cases) and the normal subjects (36 cases) were 347 +/- 63, 589 +/- 69 and 187 +/- 30 mg/dl, respectively. The mean and SEM of ATT in the heterozygotes, the homozygotes and the normal subjects were 12.5 +/- 0.4 mm, 18.6 +/- 6.6 mm, and 6.3 +/- 0.2 mm, respectively. Cutaneous xanthomas were observed in 34 out of 112 patients (30.4%). Increased ATT was observed in 95 (84.8%). IHD was diagnosed in 39 (34.8%). The ATT of FH with IHD was significantly thicker than that of FH without IHD (P less than 0.05) and that of normal subjects (p less than 0.001). Thus, the increased ATT evaluated by x-ray was the earliest clinical sign of FH and the measurement of ATT seems to be a useful adjunctive procedure for detecting familial hypercholesterolemic patients and predicting IHD in them.

Serological analysis of cell surface antigens of malignant human brain tumors

Sera from 30 patients with astrocytoma were tested for antibody reacting with cell surface antigens of cultured autologous astrocytoma cells. Ten percent of the patients had antibody detectable by mixed hemadsorption assays, approximately 50% by immune adherence and protein A assays, and 100% by anti-C3-mixed hemadsorption assays. Absorption analysis of reactive sera with autologous, allogeneic, and xenogeneic cells permitted the definition of three classes of astrocytoma cell surface antigens. Class I antigens showed an absolute restriction to autologous astrocytoma cells. Class II antigens were shared by all astrocytomas tested and could be detected also on neuroblastoma, sarcoma, and some (but not all) melanoma cell lines; these antigens were not found on cell lines derived from carcinomas or normal tissues. Class III antigens were widely distributed on cultured normal and malignant cells of human and animal origin. In this series, sera from 2 patients recognized class I antigens, 4 patients' serum recognized class II antigens, and 13 patients' sera recognized class III antigens. Absorption tests have shown that the AJ (class II) antigen of astrocytoma is serologically related to the previously described AH (class II) antigen of melanoma; in tests of nine melanoma cell lines, there was a correspondence between the AJ and AH phenotypes. This method of autologous typing provides a way to classify the cell surface antigens of astrocytomas and to assess the clinical significance of humoral immunity to these antigens.

A clinical trial of cell-wall skeleton of BCG in chemoimmunotherapy of acute leukemia

A clinical trial of chemoimmunotherapy using cell-wall skeleton of BCG (BCG-CWS) was conducted in 28 patients with acute leukemia in complete remission. Chemotherapy consisted of monthly intensification therapy for 2 months and bimonthly therafter. Immunotherapy with 200 microgram of oil-attached BCG-CWS mixed with 10(7) autochthonous leukemic cells was given intradermally at either of upper or lower extremities every week, except when the patients were on maintenance therapy. No serious systemic side effect attributable to BCG-CWS was noted. Six patients developed mild and transient temparature elevation. Most importnat side effect was local skin reaction. Indulated papules developed in all patients, resulting in draining ulcerations in 26 patients. Increase of immunological reactivity of the patients receiving BCG-CWS was noted. Skin test response to PPD, Varidase, and candida extract showed definite increase. In vitro lymphocyte blastogenic response to PPD, concanavalin-A, and pokeweed mitogen revealed significant increase.

Acute lymphoblastic leukaemia of the B-cell type refractory to intensive chemotherapy

Four patients, aged 15-50, with acute lymphoblastic leukaemia (ALL) shown to be of the B-cell type, since they formed rosettes with complement-coated sheep erythrocytes (EAC) and had lymphocytes bearing IgA on the cell surface. Clinically, they had massive leukaemic infiltration associated with hepatosplenomegaly and were extremely resistant to multiple, conventional chemotherapy, as demonstrated by prolonged therapy to achieve a remission or a short-term remission. The surface characteristics of the lymphoblasts in the circulating blood seemed to remain unchanged throughout the course of the leukaemia, despite intensive chemotherapy. The evaluation of surface markers on leukaemic cells might give better information for a forecast of the prognosis of the disease.

Serum lipids and coronary heart disease in heterozygous familial hypercholesterolemia in the Hokuriku District of Japan

The serum cholesterol and triglyceride levels and the incidence of ischemic heart disease were studied in 122 (55 men and 67 women) consecutive heterozygous familial hypercholesterolemic patients in the Hokuriku district of Japan. (1) The mean +/-SD of serum cholesterol level was 354.0 +/- 71.0 mg/100 ml, which was lower than those of the Western countries by about 60--70 mg/100 ml. (2) The mean +/-SD of serum triglyceride level was 116.5 +/- 54.0 mg/100 ml. (3) The average serum cholesterol values in the 20--50-year-old group showed no differences from those of the Western countries. However, in the above 50 years of age group the serum cholesterol levels were much lower than those in the United States. (4) The occurrence of ischemic heart disease in 83 heterozygous familial hypercholesterolemic patients was 43.3%. The incidence of myocardial infarction was 20.5%. Thus, familial hypercholesterolemia is as highly atherogenic as that of the Western countries even in Japan where the low incidence of coronary heart disease in the general population has been attributed to the low level of serum cholesterol.