This is the second issue of Pediatric Annals devoted to the subject of immunology. AH of us, I am sure, have long realized the importance of the body's natural barriers against infection with microorganisms and other foreign substances. The skin and the mucosa are the external barriers, but once an irritating abnormal substance enters the body, a whole array of bodily armaments, usually closely linked, are mobilized to counteract and in most cases, destroy the invader. This fascinating assortment includes the polymorphonuclear cells, the monocytes, the Tlymphocytes, the B-lymphocytes, the immunoglobulins, and the complement.
With such an array of bodily defenses plus our present knowledge of antibiotic therapy, it is frightening and disheartening to be faced with an uncontrollable and devastating human immunodeficiency virus (HIV), the causative agent of AIDS. This subject is well reviewed in an article in this issue by Dr. Robert Heiss.
The preceding issue of the journal covered polynuclear phagocytosis, the T-lymphocytes, the mononuclear phagocytes, humoral immunodeficiency, the correction of immunodeficiency by bone marrow transplantation, and hypersensitivity reactions and tissue injury. The symposium continues with articles on immunoglobulins, the human B cells, the complement system, lymphocyte-mediated cytotoxicity, and AIDS.
With one exception, these papers come from the Mount Sinai School of Medicine of the City University of New York where they have developed a strong division of immunology. The articles are under the Guest Editorship of Dr. Walter L. Henley, Professor of Pediatrics at the Mount Sinai School of Medicine, and Attending Pediatrician and Chief of Immunology and Infectious Disease at the Beth Israel Medical Center, New York City.
The first article is written by Dr. Henley and is titled "Structure and Genetics of Antibody." Dr. Henley first describes our modem knowledge of the structure of immunoglobulins, each molecule composed of light and heavy chains, each of which are further divided into variable and constant sections. The functions of the specific segments are described. He then notes how certain B cells differentiate into either immunoglobulin-bearing memory B cells, or plasma cells that synthesize and secrete the various classes of immunoglobulins.
The latter part of this article is devoted to the recent knowledge of the genes controlling the switch of one class of immunoglobulin to that of another. The relation of the number of genes to increased antibody diversity is described.
The second paper describes "Human B Cell Maturation and Immune Regulation," and is authored by Dr. Lloyd Mayer, Chief of the Division of Clinical Immunology, Associate Professor of Medicine; and by David Sherris, PhD, Post-Doctoral Fellow, both of the Mount Sinai Medical Center of the City University of New York.
The authors note at the outset that the Blymphocytes have one major function - the formation of antibody. They emphasize the importance of interactions with T cells and monocytes for this reaction to occur, in most cases. The B cell maturation process is clearly portrayed. The development of "memory cells" is described, noting that these cells had been primed earlier by the interaction of T cells, antigen-presenting cells, and antigen. It is noted that the first immunoglobulin produced is IgM and this is followed by switching to IgG, IgA, or IgE. But in immunodeficiency states and certain other conditions, B cell defects result in antibody deficiency, and this is dictated by the stage at which the B cell maturation is arrested.
The third contribution discusses the complement system and is presented by Dr. Bernard Adelsberg, Assistant Professor of Clinical Immunology at the Mount Sinai Hospital Medical Center.
The complement system, as noted by Dr. Adelsberg, consists of 20 or more proteins interacting with one another. The complement system has three immunological activities: the destruction of the cell membranes of cells, bacteria, viruses and fungi; the generation of small peptides which cause inflammation by mediating anaphylaxis, Chemotaxis, and vasodilation; and the immunological effects with their important roles in both the B and T cell-mediated reactions. The various pathways of the complement system are described with their specific actions. The important activities are portrayed, the attack on cell membranes and the effect directly on the membrane or indirectly through inflammation.
The following article is titled "LymphocyteMediated Cytotoxicity" and is written by Dr. Ronald B. Herberman of the Pittsburgh Cancer Institute and the Department of Medicine and Pathology of the University of Pittsburgh, Pittsburgh, Pennsylvania. I must note that Dr. Herberman is one of the national authorities on the subject, especially as it relates to the natural killer (NK) cells.
This is a most interesting article dealing primarily with the destruction of abnormal cells within the body such as bacteria, parasites, fungi, malignant cells, and normal cells of the body infected with viruses and other microorganisms. At the outset Dr. Herberman differentiates between cytotoxic Tlymphocytes and natural killer cells. What are the actions of these cells? The main stages are detailed: a) recognition of the target cell; b) binding of the effectors to the target; c) activation of the lytic material of the effector cells; d) lytic effects on the target cells; and e) effector cell-independent dissolution of the target. The method of destruction of the target cell is very well described.
The final paper, dealing with the "Immunology of AIDS" has been contributed by Dr. Robert Heiss, Assistant Professor of Pediatrics at the Mount Sinai School of Medicine of the City University of New York. He is also an Associate Attending and Chief of Pediatric Hematology/Oncology at the Beth Israel Medical Center in New York City.
This article reviews our present knowledge of this dangerous epidemic. New York City, unfortunately, has the largest incidence of AIDS in the United States and probably in the world at the present time. Most of the infants and young children are infected with this disease prenatally through the intravenous use of drugs by their mothers. Because the Beth Israel Medical Center has one of the largest drug rehabilitation centers in the city, it has among the highest number of pediatric AIDS cases. Dr. Heiss, therefore, has had the unusual opportunity to study children with the disease. A knowledge of this dangerous epidemic is important for all pediatricians. As he points out, there are more than 1 million people in the United States believed to be infected with the virus, and as of late 1986 almost 400 cases have been reported in the pediatric age group.
Most physicians have some knowledge of AIDS and the virus, the human immunodeficiency vims (HIV), that causes this breakdown of the body's immune system. This virus invades a T cell, reproduces, destroys the T cell, and then, released from the destroyed cell, attacks and destroys other T cells. An antibody is formed, but it does not confer immunity.
Dr. Heiss lists the tests presently available to detect HIV antibody, but the antibody is of no protection. He then carefully reviews the immunology of the condition, following which he turns to the specific study of AIDS in pediatrics. He notes the difference in incubation periods of infants infected in utero compared with those infected as a result of blood transfusion. The clinical picture of children suffering from the destruction of the immune system is described. The cells of these children lose their specific cytotoxic ability, and there is a lack in adequate production of immunoglobulins. This article presents the dilemma facing those who are attempting to control and finally overcome this dangerous epidemic, only first reported in 1981.