Disseminated Mycobacterium avium-intracellulare infection and red cell hypoplasia in patients with the acquired immune deficiency syndrome

Treatment of anemia in patients with HIV infection, Part 1: The need for adequate guidelines

Anemia in HIV-infected individuals, still a common hematologic complication in the highly active antiretroviral therapy (HAART) era, is associated with shortened survival, increases in the rate of disease progression, and reduction in quality of life. Based on a thorough review of the literature, guidelines were developed for the assessment, diagnosis, monitoring, and treatment of anemia in patients with HIV/AIDS by a consensus committee consisting of nurses from academia and clinical practice. A major goal of this committee is to increase awareness within the nursing community of the prevalence of anemia in HIV-infected patients and its impact on their lives. Anemia developed in close to 90% of HIV-infected patients before the introduction of HAART, and it is still found in up to 46% of patients in the HAART era. Another goal is to encourage screening for anemia and the adaptation of a proposed classification system of anemia based on a graded decrease in hemoglobin levels.

Mycobacterial complications of HIV infection

Tuberculosis is the most common opportunistic infection worldwide and is caused by the only readily transmissible pathogen among persons with HIV infection. If treatment is initiated promptly and is supervised appropriately, cure, fortunately, is highly likely. Isoniazid preventive therapy substantially reduces the risk of tuberculosis in persons with HIV infection. Of the nontuberculous mycobacteria, Mycobacterium avium complex (MAC) is the most frequent cause of disease; however, disseminated MAC disease usually is not seen until the CD4+ cell count is less than 50 cells/L. Newer agents, such as the macrolides and rifabutin, form the nucleus of treatment regimens and also are effective in preventing the disease.

Mechanisms of cytopenia in human immunodeficiency virus infection

Human immunodeficiency virus (HIV) infection often has effects on the hematopoietic system which can be distinguished from the concurrent effects of medications or opportunistic infections. Exactly how the virus mediates these effects remains uncertain, but both in vivo and in vitro studies have pointed up possible direct and indirect modes of hematopoietic suppression. Whether a significant fraction of CD34+ cells in vivo are infected with HIV remains controversial, but most studies using in situ polymerase chain reaction techniques would suggest not. Other more indirect modes of hematopoietic cell suppression such as production of autoantibodies, production of other humoral inhibitory factors, T-cell mediated suppression of hematopoiesis, or production of inhibitory or stimulatory cytokines may also be contributory. It is probable that several of these mechanisms may occur simultaneously, and an increased understanding of their role may lead to improved strategies to correct the cytopenias which often accompany HIV disease.

Impaired erythropoiesis in the acquired immunodeficiency syndrome with disseminated Mycobacterium avium complex

PURPOSE

Anemia is an important negative predictor for survival with disseminated Mycobacterium avium complex (MAC) infection in the acquired immunodeficiency syndrome (AIDS). We analyzed the differences in AIDS patients with and without MAC infection with regard to anemia, severity of human immunodeficiency virus (HIV) infection, bone marrow morphology, and bone marrow erythroid progenitor colony growth (BFU-E and CFU-E). In addition, we determined the in vitro effect of sera obtained from these patients on normal BFU-E and CFU-E. A possible role of macrophages in the suppression of erythropoiesis was examined by studying in vitro the effect of supernatants from MAC-infected macrophages on cultured BFU-E and CFU-E.

PATIENTS AND METHODS

Hematocrit, serum levels of p24 antigen, erythropoietin, and CD4-positive cell count were determined in 14 AIDS patients with and 24 without MAC infection. Bone marrow erythropoietic and granulocytic progenitor cells from 15 normal individuals, from 12 AIDS patients with MAC infection, and from 10 AIDS patients without MAC infection were cultured on methylcellulose. In addition, progenitor cells from normal individuals were cultured in the presence, and in the absence, of sera obtained from AIDS patients with (14), or without (24), MAC infection. Last, we studied the effect of supernatants (SNs) from MAC and Mycobacterium tuberculosis-infected macrophages on erythropoietic progenitor cell growth.

RESULTS

The anemia in AIDS patients with MAC infection was associated with a selective suppression of erythropoietic progenitors despite bone marrow morphology that was indistinguishable from that in patients without MAC infection. The degree of anemia could not be explained on the basis of severity of HIV infection or a deficiency of erythropoietin production. Bone marrow mononuclear cells from AIDS patients with MAC generated significantly fewer erythroid progenitor colonies (BFU-E and CFU-E) than equivalent cells from AIDS patients without MAC infection (p < 0.05). Sera from MAC-infected AIDS patients were markedly inhibitory to the erythroid progenitors as compared with sera from patients without MAC infection (p < 0.001). SNs from MAC-infected macrophages were markedly inhibitory to the erythroid progenitors (BFU-E and CFU-E) as compared with the myeloid progenitors (CFU-GM).

CONCLUSION

The profound anemia in MAC-infected AIDS patients is due to suppression of erythroid progenitors by a soluble factor(s) in the serum. The data suggest that the soluble factor(s) is probably elaborated by macrophages.

The effects of HIV on hematopoiesis

Hematologic abnormalities are commonly associated with infection by the human immunodeficiency virus (HIV) that is the etiologic agent of the acquired immunodeficiency syndrome (AIDS). Bone marrow examinations reveal frequent dysplasia, dyserythropoïesis, lymphocytic infiltration and plasmocytosis. These marrow morphologic characteristics are strongly associated with peripheral blood cytopenia of one or more lineage: anemia, granulocytopenia or thrombocytopenia are frequently described. The pathophysiology of these observed deficiencies is still unclear, although several mechanisms have been postulated as possible explanations for the hematological features of AIDS patients. The hematologic manifestations observed in patients with AIDS or AIDS-related complex (ARC) and the postulated pathogenetic mechanisms are discussed in this review.

Severe anemia is an important negative predictor for survival with disseminated Mycobacterium avium-intracellulare in acquired immunodeficiency syndrome

Disseminated Mycobacterium avium-intracellulare (MAI) in patients with the acquired immunodeficiency syndrome (AIDS) is usually unresponsive to antimycobacterial therapy. We examined clinical and laboratory characteristics of MAI organisms and their relationship to the length of survival. We studied factors influencing survival and compared these in 76 patients with AIDS with and without MAI. Serum levels of p24 antigen and erythropoietin, and CD4-positive helper T-lymphocytes in blood were assessed in 36 additional patients with various clinical stages of HIV infection. In patients with MAI infection, survival was significantly related only to total lymphocyte count, hematocrit, platelet count, and sex. Of these, hematocrit and total lymphocyte count were the only linear predictors of survival. Anemia was significantly more profound in patients with AIDS and MAI than in the other patients. This anemia in patients with MAI could not be ascribed to increased peripheral destruction of red cells, deficient nutritional factors, or erythropoietin production, HIV viral or bacterial load, or a general effect on other blood elements such as neutrophils or platelets. The influence of MAI on survival in patients with AIDS did depend upon whether the MAI occurred as an index infection or was preceded by other opportunistic infections. Patients with other preceding opportunistic infection lived for a much shorter duration from the time of diagnosis of MAI.

The carbohydrate- and lipid-containing cell wall of mycobacteria, phenolic glycolipids: structure and immunological properties

Phenolic glycolipids were first discovered as cell-wall constituents of M. bovis, M. bovis BCG, M. marinum, and M. kansasii. Recently, such compounds were also isolated from M. leprae and have been shown to be specific-species serological markers. Moreover, they seem to be involved, in the case of lepromatous leprosy, in the stimulation of the suppressor T-cells. The functional activities of these phenolic glycolipids over the immune cells stimulation emphasized the role played by these molecules in the mycobacteria pathogenicity. Phenolic glycolipids have also been found in M. gastri and M. tuberculosis strain Canetti. From a structural point of view, these glycolipids contain the same aglycon moiety mainly assigned to phenolphthiocerol diester while the sugar part structure confers to some of these glycolipids their antigenic specificity. The search of immunoreactive glycolipids and their function analysis remain a challenge for chemists and immunologists for the understanding of the mycobacteria pathogenicity.

Septicaemia in patients with AIDS

During a 5 year period at St Stephen's hospital, London, septicaemia was detected in 66 patients with the acquired immune deficiency syndrome (AIDS) and in 13 other patients with non-AIDS-associated HIV infections. The most frequent pathogens in patients with AIDS were Mycobacterium avium-intracellulare, Streptococcus pneumoniae, Pseudomonas aeruginosa, Cryptococcus neoformans and staphylococci. A series of HIV-associated septicaemias reported from other centres in different countries has shown great variation in the pattern of aetiological agents observed, which may partly reflect differences in the local socio-economic condition, ethnic backgrounds, other predisposing factors, and blood culture techniques. Salmonella species were a prominent cause of septicaemia in several reports. Most centres have also reported an increasing problem with septicaemias associated with intravenous lines in patients receiving antiviral or other parenteral drug therapy.

Non-cryptosporidial diarrhoea in human immunodeficiency virus (HIV) infected patients

Thirty of 81 consecutive HIV antibody positive patients referred with non-cryptosporidial diarrhoea had no potential infectious cause; most had AIDS related complex rather than the full blown syndrome. Opportunistic infections with cytomegalovirus (CMV), mycobacterium avium-intracellulare (MAI), and herpes simplex virus (HSV), which allowed a diagnosis of AIDS to be made, were found in 19 patients and were the presenting features of AIDS in five. Other potential pathogenic species included entamoeba, giardia, campylobacter, and salmonella (without septicaemia). Cytomegalovirus infection was often accompanied by abdominal pain. Severe weight loss (greater than 10 kg) at presentation was found in patients with CMV infection and MAI. Bloody diarrhoea was confined to the group with HSV procitis. Malignant causes of diarrhoea were rare. Two patients developed a squamous carcinoma of the anorectal margin and one a non-Hodgkin's lymphoma. In only two of 12 patients who had Kaposi's sarcoma was this considered as a cause of diarrhoea. Rigid sigmoidoscopy showed macroscopic abnormalities in over a third (32) of the 81 patients with non-cryptosporidial diarrhoea. Most commonly this was severe inflammation (17) or discrete ulceration (four) [three of whom had CMV colitis]. Kaposi's sarcoma was identified in 11 patients. Non-specific inflammation was seen histologically in 40 of the 60 patients with no sigmoidoscopic inflammatory changes. Barium enema only revealed an abnormality in a minority of the patients and a colonoscopy only revealed information additional to rigid sigmoidoscopy in two patients--one with CMV ulcers in the transverse colon and the other with evidence of Kaposi's sarcoma not seen in the rectum. Ten patients had a rectal biopsy examined by electron microscopy as no infective cause of diarrhoea was uncovered. In four of these microtubular structures which are commonly seen in viral infections were found and two had prelymphomatous changes and in one of these frank lymphoma has developed. We recommend multiple stool analysis, sigmoidoscopy and rectal biopsy as the initial investigations in these patients reserving tests of malabsorption, colonoscopy, and barium enema for the small number of more difficult cases.