Validation of self-reported complications by bone marrow transplantation survivors

Self-administered questionnaires are commonly used to measure exposures and outcomes in epidemiological research and thus need good validity. With increasing numbers of cancer survivors, there is interest in the ongoing assessment of therapy-related complications. A medical record validation of patient-reported complications following bone marrow transplantation (BMT) was performed using a self-administered questionnaire. The study population consisted of 100 patients who had undergone BMT at the City of Hope. The following self-reported complications were validated using medical records: ocular, endocrine, cardiovascular, musculoskeletal, pulmonary, gastrointestinal, neurological, graft-versus-host disease, and subsequent cancers. Using information from medical records as the standard, sensitivities ranged from 52.9% for subsequent cancers to 100% for avascular necrosis and hypothyroidism. Specificities ranged from 75.4% for ocular complications to 100% for avascular necrosis. There was intermediate to excellent agreement (kappa = 0. 4-1.0) for all complications evaluated. Thus, the agreement between self-reporting and medical records was good for complications with clear diagnostic criteria that are easily communicated to the patient, but was diminished for complications with non-established diagnostic criteria (xerophthalmia) or a fluctuating course (peripheral neuropathies and hypertension). Overall these results suggest that cancer survivors can self-report serious complications with an acceptable level of accuracy in epidemiological research.

Second primary tumors in patients with cutaneous malignant melanoma

BACKGROUND

Several studies report coexistent or subsequent primary tumors (SPT) among patients with malignant melanoma (MM), with the rate of incidence ranging from 1.5-20% depending on the sample size and the length and completeness of follow-up.

METHODS

The authors followed a cohort of patients with cutaneous MM who were diagnosed and treated at the City of Hope National Medical Center to determine the incidence rate of SPT and associated risk factors. Five hundred eighty-five patients (median age at diagnosis, 43 years) were diagnosed and treated for MM between 1952 and 1996 and followed for a median of 6.5 years (range, 0.0-37.0 years). Ninety-six percent of the cohort had been treated by surgery alone.

RESULTS

Thirty-seven patients developed an SPT. These included skin cancers (n = 23), carcinoma of the urinary bladder, breast carcinoma, and lymphoma (n = 3 each), lung carcinoma and prostate carcinoma (n = 2 each), and cervical carcinoma (n = 1). The estimated cumulative rate of incidence after MM was 5% at 5 years for any SPT, 3.7% for a second skin cancer, and 1.1% for a second solid tumor. Overall, the current cohort of MM patients was found to be at an increased risk for developing a subsequent melanoma (standardized incidence ratio [SIR], 4.5; 95% confidence interval [95% CI], 1.2-10.0) when compared with the general population. Older men (age > 50 years at the time of diagnosis of MM) were at an increased risk of developing subsequent bladder carcinoma (SIR, 6.4; 95% CI, 1.2-15.7).

CONCLUSIONS

Patients diagnosed with MM are at an increased risk of developing subsequent MM and bladder carcinoma. Issues to be addressed in future studies include interactions between environmental exposures and genetic susceptibility and the identification of individuals at increased risk.

Modulation of terminal deoxynucleotidyltransferase activity by the DNA-dependent protein kinase

Rare Ig and TCR coding joints can be isolated from mice that have a targeted deletion in the gene encoding the 86-kDa subunit of the Ku heterodimer, the regulatory subunit of the DNA-dependent protein kinase (DNA-PK). However in the coding joints isolated from Ku86-/- animals, there is an extreme paucity of N regions (the random nucleotides added during V(D)J recombination by the enzyme TdT). This finding is consistent with a decreased frequency of coding joints containing N regions isolated from C.B-17 SCID mice that express a truncated form of the catalytic subunit of the DNA-PK (DNA-PKCS). This finding suggests an unexpected role for DNA-PK in addition of N nucleotides to coding ends during V(D)J recombination. In this report, we establish that TdT forms a stable complex with DNA-PK. Furthermore, we show that DNA-PK modulates TdT activity in vitro by limiting both the length and composition of nucleotide additions.

Targeted deletion of the IgA constant region in mice leads to IgA deficiency with alterations in expression of other Ig isotypes

A murine model of IgA deficiency has been established by targeted deletion of the IgA switch and constant regions in embryonic stem cells. B cells from IgA-deficient mice were incapable of producing IgA in vitro in response to TGF-beta. IgA-deficient mice expressed higher levels of IgM and IgG in serum and gastrointestinal secretions and decreased levels of IgE in serum and pulmonary secretions. Expression of IgG subclasses was complex, with the most consistent finding being an increase in IgG2b and a decrease in IgG3 in serum and secretions. No detectable IgA Abs were observed following mucosal immunization against influenza; however, compared with those in wild-type mice, increased levels of IgM Abs were seen in both serum and secretions. Development of lymphoid tissues as well as T and B lymphocyte function appeared normal otherwise. Peyer's patches in IgA-deficient mice were well developed with prominent germinal centers despite the absence of IgA in these germinal centers or intestinal lamina propria. Lymphocytes from IgA-deficient mice responded to T and B cell mitogens comparable to those of wild-type mice, while T cells from IgA-deficient mice produced comparable levels of IFN-gamma and IL-4 mRNA and protein. In conclusion, mice with targeted deletion of the IgA switch and constant regions are completely deficient in IgA and exhibit altered expression of other Ig isotypes, notably IgM, IgG2b, IgG3, and IgE, but otherwise have normal lymphocyte development, proliferative responses, and cytokine production.

Mechanism of V(D)J recombination

V(D)J recombination can be separated into two basic operations: DNA cleavage and joining of broken ends. Our understanding of both reactions has increased substantially in the past year. Major advances include the development of a cell-free system capable of cleavage and the identification of several proteins involved in both V(D)J recombination and double-strand break repair.

The level of N-region diversity in T cell receptors is not pre-ordained in the stem cell

The alpha beta T cell repertoires of adults and neonates are distinctly different. For example, T cell receptors (TcR) from adult animals have substantial N-nucleotide addition at their V-D-J junctions while those from neonatal animals do not. This dichotomy reflects a rather abrupt change in expression of the terminal deoxynucleotidyl transferase (TdT) gene in thymocytes on day 4 after birth. We have asked whether this change is due to the differentiation of successive waves of stem cells harboring different potentials for TdT expression, a scenario like the one proposed to explain developmental regulation of gamma delta T cell repertoires. Reconstitution of adult severe combined immunodeficiency mice with either fetal liver or adult bone marrow precursors gave rise to T cells with substantial N-region diversity in their TcR, even at the earliest points of reconstitution. It is most likely, then, that the abrupt change in TdT gene expression in day 4 thymocytes is due to an environmentally induced switch-on.

Regulation of N-region diversity in antigen receptors through thymocyte differentiation and thymus ontogeny

The random addition of "N nucleotides" by terminal deoxynucleotidyltransferase (TdT) is an important component of the diversity of T-cell receptor genes. We have investigated the expression of TdT during thymocyte differentiation and thymus ontogeny. TdT gene transcripts are confined to immature thymocytes of the cortex, being down-regulated concomitantly with recombination-activating gene transcripts after positive selection of mature medullary T cells. According to in situ hybridization, TdT RNA is absent from the neonatal thymus, but it appears 3 to 5 days after birth, just before the appearance of significant N-region diversity in T-cell receptor junctional sequences but clearly after the thymus attains competence at clonal deletion.

Evaluation of the functional equivalence of major histocompatibility complex class II A and E complexes

Most mice display two conventional major histocompatibility complex class II isotypes, A and E. Several A+E- strains have been observed, but never any that are A-E+. Because of this and because of hints from several lines of functional analysis, it has been proposed that the two isotypes might not operate equivalently. This proposition has not been directly testable until now because of the lack of an E-only strain. We report the production of such mice, exploiting previously created class II-transgenic and class II-"knock-out" lines. A+E-, A-E-, and A-E+ littermates have been compared by a number of parameters. We find that E and A molecules are, for the most part, functionally equivalent. However, subtle differences are seen in their ability to engage CD4 molecules on immature thymocytes, and in the profile of receptors on T cells selected into the periphery.

A special repertoire of alpha:beta T cells in neonatal mice

According to several functional criteria, the mature thymocytes of neonatal and adult mice are distinctly different. We wondered whether these differences in function might have a structural correlate: do neonates have a distinct repertoire of alpha:beta T cells? In this study, we have exploited the power of polymerase chain reaction technology to generate large numbers of T cell receptor sequences from sorted thymocyte populations from newborn and adult mice. The newborn-derived sequences show very few N nucleotide additions, usually the major source of diversity in T cell receptors. Most interestingly, the paucity of N insertions appears to be exaggerated by selection events that operate during T cell differentiation in the thymus. The significance of these results is largely: (i) that they parallel recent findings on the B cell repertoire in neonates, raising questions about the reactivities specified by such a special repertoire; and (ii) that they suggest a means to 'tag' T cells exported perinatally, allowing one to test the premise that autoreactive T cells derive preferentially from the newborn repertoire.